diff --git a/web/src/coaster/AccelerationStripsPanel.module.css b/web/src/coaster/AccelerationStripsPanel.module.css
index 3c03966..c9dd9f4 100644
--- a/web/src/coaster/AccelerationStripsPanel.module.css
+++ b/web/src/coaster/AccelerationStripsPanel.module.css
@@ -1,9 +1,5 @@
 .panel {
-  position: fixed;
-  right: 16px;
-  top: 60px;
-  z-index: 600;
-  width: 280px;
+  width: 340px;
   background: rgba(8, 8, 12, 0.84);
   backdrop-filter: blur(10px);
   -webkit-backdrop-filter: blur(10px);
@@ -57,7 +53,7 @@
 .stripRow {
   display: flex;
   align-items: center;
-  gap: 6px;
+  gap: 5px;
   margin-bottom: 6px;
   font-size: 12px;
 }
@@ -66,37 +62,17 @@
   color: rgba(245, 158, 11, 0.9);
   font-weight: 600;
   min-width: 44px;
+  flex-shrink: 0;
 }
 
-.stripRange {
-  color: rgba(255, 255, 255, 0.38);
-  font-size: 11px;
-  min-width: 56px;
-}
-
-.accelInput {
-  width: 50px;
-  background: rgba(255, 255, 255, 0.07);
-  border: 1px solid rgba(255, 255, 255, 0.14);
-  border-radius: 6px;
-  color: #fff;
-  font-size: 13px;
-  font-weight: 600;
-  padding: 2px 5px;
-  text-align: right;
-}
-.accelInput:focus {
-  outline: none;
-  border-color: rgba(245, 158, 11, 0.5);
-}
-
-.stripUnit {
+.rangeSep {
   color: rgba(255, 255, 255, 0.28);
   font-size: 11px;
 }
 
 .stripDelete {
   margin-left: auto;
+  flex-shrink: 0;
   width: 20px;
   height: 20px;
   border-radius: 4px;
diff --git a/web/src/coaster/AccelerationStripsPanel.tsx b/web/src/coaster/AccelerationStripsPanel.tsx
index ef695f8..28e6a00 100644
--- a/web/src/coaster/AccelerationStripsPanel.tsx
+++ b/web/src/coaster/AccelerationStripsPanel.tsx
@@ -1,16 +1,16 @@
 import { useState, useEffect } from 'react'
 import type { AccelerationStrip } from '../types/api'
+import { BlenderInput } from '../ui/BlenderInput'
 import styles from './AccelerationStripsPanel.module.css'
 
 interface Props {
   strips: AccelerationStrip[]
   onRemoveStrip: (id: string) => void
   onUpdateStrip: (id: string, accel_ms2: number) => void
+  onUpdateStripFrac: (id: string, startFrac: number, endFrac: number) => void
 }
 
-function pct(v: number) { return `${(v * 100).toFixed(0)}%` }
-
-export function AccelerationStripsPanel({ strips, onRemoveStrip, onUpdateStrip }: Props) {
+export function AccelerationStripsPanel({ strips, onRemoveStrip, onUpdateStrip, onUpdateStripFrac }: Props) {
   const [open, setOpen] = useState(true)
 
   // Auto-open when a strip is added
@@ -31,19 +31,45 @@ export function AccelerationStripsPanel({ strips, onRemoveStrip, onUpdateStrip }
             : strips.map((s, i) => (
               <div key={s.id} className={styles.stripRow}>
                 <span className={styles.stripIndex}>Strip {i + 1}</span>
-                <span className={styles.stripRange}>
-                  {pct(s.startFrac)}–{pct(s.endFrac)}
-                </span>
-                <input
-                  type="number"
-                  step={0.5}
+
+                <BlenderInput
+                  value={s.startFrac * 100}
+                  onChange={v => {
+                    const sf = Math.max(0, Math.min(v / 100, s.endFrac - 0.001))
+                    onUpdateStripFrac(s.id, sf, s.endFrac)
+                  }}
+                  min={0}
+                  max={s.endFrac * 100 - 0.1}
+                  step={0.2}
+                  decimals={1}
+                  suffix="%"
+                />
+
+                <span className={styles.rangeSep}>–</span>
+
+                <BlenderInput
+                  value={s.endFrac * 100}
+                  onChange={v => {
+                    const ef = Math.min(100, Math.max(v / 100, s.startFrac + 0.001))
+                    onUpdateStripFrac(s.id, s.startFrac, ef)
+                  }}
+                  min={s.startFrac * 100 + 0.1}
+                  max={100}
+                  step={0.2}
+                  decimals={1}
+                  suffix="%"
+                />
+
+                <BlenderInput
+                  value={s.accel_ms2}
+                  onChange={v => onUpdateStrip(s.id, v)}
                   min={-50}
                   max={50}
-                  value={s.accel_ms2}
-                  onChange={e => onUpdateStrip(s.id, Number(e.target.value))}
-                  className={styles.accelInput}
+                  step={0.1}
+                  decimals={1}
+                  suffix="m/s²"
                 />
-                <span className={styles.stripUnit}>m/s²</span>
+
                 <button
                   className={styles.stripDelete}
                   onClick={() => onRemoveStrip(s.id)}
diff --git a/web/src/coaster/CoasterEditorPage.module.css b/web/src/coaster/CoasterEditorPage.module.css
index f1cafc3..015975a 100644
--- a/web/src/coaster/CoasterEditorPage.module.css
+++ b/web/src/coaster/CoasterEditorPage.module.css
@@ -516,6 +516,20 @@
   margin: 0 4px;
 }
 
+/* ── Right panel column ──────────────────────────────────────────────────────── */
+
+.rightColumn {
+  position: fixed;
+  right: 16px;
+  top: 60px;
+  z-index: 600;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  max-height: calc(100vh - 76px);
+  overflow-y: auto;
+}
+
 /* ── Loading overlay ─────────────────────────────────────────────────────────── */
 
 .loading {
diff --git a/web/src/coaster/CoasterEditorPage.tsx b/web/src/coaster/CoasterEditorPage.tsx
index a03be6e..151fda1 100644
--- a/web/src/coaster/CoasterEditorPage.tsx
+++ b/web/src/coaster/CoasterEditorPage.tsx
@@ -118,10 +118,12 @@ function CoasterEditorScene({ challengeId, challenge, readonly = false, preloadC
   // Exit ride mode whenever the sim result changes; clear cursor on exit
   useEffect(() => { setIsRideMode(false); setRideCursor(null) }, [simResult])
 
-  // Suspend Cesium's render loop while Three.js ride view is active so both
-  // renderers don't compete for the GPU simultaneously.
+  // Suspend Cesium while Three.js ride view is active: stop the render loop AND
+  // disable the globe so Cesium's terrain web-workers stop posting decode results
+  // back to the main thread (those async completions caused periodic ~5 s spikes).
   useEffect(() => {
-    viewer.useDefaultRenderLoop = !isRideMode
+    viewer.useDefaultRenderLoop  = !isRideMode
+    viewer.scene.globe.enabled   = !isRideMode
   }, [isRideMode, viewer])
 
   // Refs for simulation result entities (cleared on each new run / unmount)
@@ -135,10 +137,12 @@ function CoasterEditorScene({ challengeId, challenge, readonly = false, preloadC
     const coords = challenge.region.coordinates[0]
     const positions = coords.map(([lon, lat]) => Cesium.Cartesian3.fromDegrees(lon, lat))
     const sphere = Cesium.BoundingSphere.fromPoints(positions, new Cesium.BoundingSphere())
-    sphere.radius = Math.max(sphere.radius + 20, 50)
+    // Add 25 % padding so the polygon doesn't butt right up against the frame
+    // edges, then let Cesium compute the exact range (range = 0 = auto-fit).
+    const padded = new Cesium.BoundingSphere(sphere.center, sphere.radius * 1.25)
 
-    viewer.camera.flyToBoundingSphere(sphere, {
-      offset: new Cesium.HeadingPitchRange(0, Cesium.Math.toRadians(-78), sphere.radius * 3),
+    viewer.camera.flyToBoundingSphere(padded, {
+      offset: new Cesium.HeadingPitchRange(0, Cesium.Math.toRadians(-60), 0),
       duration: 1.2,
     })
   }, [challenge, viewer])
@@ -324,7 +328,6 @@ function CoasterEditorScene({ challengeId, challenge, readonly = false, preloadC
           simResult={simResult}
           captureData={terrain.captureData}
           onStop={() => { setIsRideMode(false); setRideCursor(null) }}
-          onRideProgress={setRideCursor}
         />
       )}
 
@@ -496,7 +499,7 @@ function CoasterEditorScene({ challengeId, challenge, readonly = false, preloadC
       )}
 
       {/* ── Simulation profile charts (left panel) ──────────────────────── */}
-      {simResult?.profile && (
+      {!isRideMode && simResult?.profile && (
         <SimulationPlots
           profile={simResult.profile}
           strips={accel.strips}
@@ -504,23 +507,26 @@ function CoasterEditorScene({ challengeId, challenge, readonly = false, preloadC
         />
       )}
 
-      {/* ── Acceleration strips (right panel) ───────────────────────────── */}
-      {accel.strips.length > 0 && (
-        <AccelerationStripsPanel
-          strips={accel.strips}
-          onRemoveStrip={accel.removeStrip}
-          onUpdateStrip={accel.updateStrip}
-        />
-      )}
-
-      {/* ── Coaster list panel (right) ───────────────────────────────────── */}
-      {challengeId && (
-        <CoasterListPanel
-          challengeId={challengeId}
-          currentUsername={currentUsername}
-          onLoad={handleLoad}
-          refreshKey={coasterListKey}
-        />
+      {/* ── Right panel column (acceleration strips + coaster list) ────── */}
+      {!isRideMode && (
+        <div className={styles.rightColumn}>
+          {accel.strips.length > 0 && (
+            <AccelerationStripsPanel
+              strips={accel.strips}
+              onRemoveStrip={accel.removeStrip}
+              onUpdateStrip={accel.updateStrip}
+              onUpdateStripFrac={accel.updateStripFrac}
+            />
+          )}
+          {challengeId && (
+            <CoasterListPanel
+              challengeId={challengeId}
+              currentUsername={currentUsername}
+              onLoad={handleLoad}
+              refreshKey={coasterListKey}
+            />
+          )}
+        </div>
       )}
 
       {/* ── Loading overlay ──────────────────────────────────────────────── */}
diff --git a/web/src/coaster/CoasterListPanel.module.css b/web/src/coaster/CoasterListPanel.module.css
index 26acd5c..a82e96d 100644
--- a/web/src/coaster/CoasterListPanel.module.css
+++ b/web/src/coaster/CoasterListPanel.module.css
@@ -1,8 +1,4 @@
 .panel {
-  position: fixed;
-  right: 16px;
-  top: 112px; /* 52px header + ~44px topBar + 16px gap */
-  z-index: 200;
   width: 240px;
   background: rgba(8, 8, 12, 0.84);
   backdrop-filter: blur(10px);
diff --git a/web/src/coaster/RideRenderer.tsx b/web/src/coaster/RideRenderer.tsx
index 93371ec..c7fa31d 100644
--- a/web/src/coaster/RideRenderer.tsx
+++ b/web/src/coaster/RideRenderer.tsx
@@ -249,9 +249,20 @@ function buildScene(captureData: TerrainCaptureData[], rideData: RideData, rende
   addRail(rideData.rail1)
   addRail(rideData.rail2)
 
+  // Expose a warm-up helper: makes every terrain patch visible so the caller can
+  // do one render that forces the GPU driver to flush all queued texImage2D /
+  // generateMipmap commands for every patch at once.  Without this, those
+  // commands are deferred and cause a GPU pipeline stall the first time each
+  // patch becomes the active (visible) one during the ride — which at high
+  // coaster speeds can be every few seconds.
+  function warmUpPatches() {
+    terrainMeshes.forEach(m => { m.visible = true })
+  }
+
   return {
     scene,
     setActivePatch,
+    warmUpPatches,
     disposeAll: () => {
       geos.forEach(g => g.dispose())
       mats.forEach(m => m.dispose())
@@ -322,7 +333,7 @@ export function RideRenderer({ simResult, captureData, onStop, onRideProgress }:
     rideDataRef.current = rideData
     setTotalDuration(rideData.totalDuration)
 
-    const { scene, setActivePatch, disposeAll } = buildScene(captureData, rideData, renderer)
+    const { scene, setActivePatch, warmUpPatches, disposeAll } = buildScene(captureData, rideData, renderer)
     sceneRef.current       = scene
     setActivePatchRef.current = setActivePatch
     activePatchIdxRef.current = 0
@@ -345,7 +356,13 @@ export function RideRenderer({ simResult, captureData, onStop, onRideProgress }:
       cameraRef.current.updateMatrixWorld()
     }
 
+    // Warm-up: make every terrain patch visible and render once.  This forces the
+    // GPU driver to flush all pending texImage2D / generateMipmap commands for
+    // every patch right now, so patch-visibility switches during the ride have
+    // zero GPU stall cost.  Then reset to only the first patch.
+    warmUpPatches()
     renderer.render(scene, cameraRef.current)
+    setActivePatch(0)
 
     return () => {
       window.removeEventListener('resize', onResize)
diff --git a/web/src/coaster/useAccelerationStrips.ts b/web/src/coaster/useAccelerationStrips.ts
index be48ca4..aa96776 100644
--- a/web/src/coaster/useAccelerationStrips.ts
+++ b/web/src/coaster/useAccelerationStrips.ts
@@ -43,6 +43,7 @@ export interface AccelerationStripsHandle {
   strips: AccelerationStrip[]
   removeStrip: (id: string) => void
   updateStrip: (id: string, accel_ms2: number) => void
+  updateStripFrac: (id: string, startFrac: number, endFrac: number) => void
   clearStrips: () => void
   loadStrips: (strips: AccelerationStrip[]) => void
 }
@@ -75,6 +76,10 @@ export function useAccelerationStrips(
     setStrips(prev => prev.map(s => s.id === id ? { ...s, accel_ms2 } : s))
   }, [])
 
+  const updateStripFrac = useCallback((id: string, startFrac: number, endFrac: number) => {
+    setStrips(prev => prev.map(s => s.id === id ? { ...s, startFrac, endFrac } : s))
+  }, [])
+
   const clearStrips = useCallback(() => {
     setStrips([])
   }, [])
@@ -236,5 +241,5 @@ export function useAccelerationStrips(
     }
   }, [viewer])
 
-  return { strips, removeStrip, updateStrip, clearStrips, loadStrips }
+  return { strips, removeStrip, updateStrip, updateStripFrac, clearStrips, loadStrips }
 }
diff --git a/web/src/coaster/useTerrainCapture.ts b/web/src/coaster/useTerrainCapture.ts
index 907ca20..86ea1fa 100644
--- a/web/src/coaster/useTerrainCapture.ts
+++ b/web/src/coaster/useTerrainCapture.ts
@@ -207,7 +207,7 @@ export function useTerrainCapture(
 
     if (!simResult) {
       setStatus('idle')
-      return
+      return () => { abortRef.current = true }
     }
 
     abortRef.current = false
@@ -224,6 +224,10 @@ export function useTerrainCapture(
         console.error('Terrain capture failed:', err)
         setStatus('error')
       })
+
+    return () => {
+      abortRef.current = true
+    }
   }, [simResult, viewer])
 
   return { status, captureData }
diff --git a/web/src/ui/BlenderInput.module.css b/web/src/ui/BlenderInput.module.css
new file mode 100644
index 0000000..0babf87
--- /dev/null
+++ b/web/src/ui/BlenderInput.module.css
@@ -0,0 +1,50 @@
+.root {
+  display: inline-flex;
+  align-items: center;
+  cursor: ew-resize;
+  user-select: none;
+}
+
+.display {
+  display: inline-flex;
+  align-items: center;
+  gap: 2px;
+  background: rgba(255, 255, 255, 0.07);
+  border: 1px solid rgba(255, 255, 255, 0.14);
+  border-radius: 5px;
+  color: #fff;
+  font-size: 12px;
+  font-weight: 600;
+  padding: 2px 6px;
+  min-width: 40px;
+  text-align: right;
+  justify-content: flex-end;
+  white-space: nowrap;
+  transition: border-color 0.12s, background 0.12s;
+}
+
+.root:hover .display {
+  background: rgba(255, 255, 255, 0.11);
+  border-color: rgba(245, 158, 11, 0.45);
+}
+
+.suffix {
+  font-size: 10px;
+  font-weight: 400;
+  color: rgba(255, 255, 255, 0.35);
+  margin-left: 2px;
+}
+
+.input {
+  width: 64px;
+  background: rgba(245, 158, 11, 0.15);
+  border: 1px solid rgba(245, 158, 11, 0.6);
+  border-radius: 5px;
+  color: #fff;
+  font-size: 12px;
+  font-weight: 600;
+  padding: 2px 6px;
+  outline: none;
+  cursor: text;
+  text-align: right;
+}
diff --git a/web/src/ui/BlenderInput.tsx b/web/src/ui/BlenderInput.tsx
new file mode 100644
index 0000000..034767e
--- /dev/null
+++ b/web/src/ui/BlenderInput.tsx
@@ -0,0 +1,112 @@
+import { useRef, useState, useCallback, useEffect } from 'react'
+import styles from './BlenderInput.module.css'
+
+interface Props {
+  value: number
+  onChange: (v: number) => void
+  min?: number
+  max?: number
+  /** How much the value changes per pixel dragged. Default 0.1 */
+  step?: number
+  /** Decimal places shown. Default 1 */
+  decimals?: number
+  /** Optional suffix shown after the number, e.g. "%" or "m/s²" */
+  suffix?: string
+}
+
+const DRAG_THRESHOLD = 4  // px before we treat motion as a drag
+
+function clamp(v: number, min: number | undefined, max: number | undefined) {
+  if (min !== undefined && v < min) return min
+  if (max !== undefined && v > max) return max
+  return v
+}
+
+export function BlenderInput({ value, onChange, min, max, step = 0.1, decimals = 1, suffix }: Props) {
+  const [editing, setEditing] = useState(false)
+  const [text, setText] = useState('')
+  const inputRef = useRef<HTMLInputElement>(null)
+  const dragState = useRef<{
+    startX: number
+    startValue: number
+    moved: boolean
+  } | null>(null)
+
+  // ── Focus the real input when we enter edit mode ────────────────────────────
+  useEffect(() => {
+    if (editing) {
+      inputRef.current?.select()
+    }
+  }, [editing])
+
+  // ── Mouse-down: begin drag tracking ────────────────────────────────────────
+  const handleMouseDown = useCallback((e: React.MouseEvent) => {
+    if (editing) return
+    e.preventDefault()
+    dragState.current = { startX: e.clientX, startValue: value, moved: false }
+
+    function onMove(me: MouseEvent) {
+      if (!dragState.current) return
+      const dx = me.clientX - dragState.current.startX
+      if (Math.abs(dx) >= DRAG_THRESHOLD) {
+        dragState.current.moved = true
+        const next = clamp(
+          dragState.current.startValue + dx * step,
+          min,
+          max,
+        )
+        onChange(next)
+      }
+    }
+
+    function onUp() {
+      if (!dragState.current) return
+      if (!dragState.current.moved) {
+        // treat as a click → enter edit mode
+        setText(value.toFixed(decimals))
+        setEditing(true)
+      }
+      dragState.current = null
+      window.removeEventListener('mousemove', onMove)
+      window.removeEventListener('mouseup', onUp)
+    }
+
+    window.addEventListener('mousemove', onMove)
+    window.addEventListener('mouseup', onUp)
+  }, [editing, value, step, min, max, decimals, onChange])
+
+  // ── Commit text input ───────────────────────────────────────────────────────
+  const commit = useCallback(() => {
+    const parsed = parseFloat(text)
+    if (!isNaN(parsed)) {
+      onChange(clamp(parsed, min, max))
+    }
+    setEditing(false)
+  }, [text, min, max, onChange])
+
+  const handleKeyDown = useCallback((e: React.KeyboardEvent) => {
+    if (e.key === 'Enter') commit()
+    if (e.key === 'Escape') setEditing(false)
+  }, [commit])
+
+  return (
+    <span className={styles.root} onMouseDown={handleMouseDown}>
+      {editing ? (
+        <input
+          ref={inputRef}
+          className={styles.input}
+          value={text}
+          onChange={e => setText(e.target.value)}
+          onBlur={commit}
+          onKeyDown={handleKeyDown}
+          onClick={e => e.stopPropagation()}
+        />
+      ) : (
+        <span className={styles.display}>
+          {value.toFixed(decimals)}
+          {suffix && <span className={styles.suffix}>{suffix}</span>}
+        </span>
+      )}
+    </span>
+  )
+}