fixing-motion-performance

Name: fixing-motion-performance
Author: ibelick

byibelick· 7 skills

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How to install fixing-motion-performance?

ibelick/ui-skills/fixing-motion-performance

$npx -y skills add ibelick/ui-skills --skill fixing-motion-performance

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Run `npx skills use "https://github.com/ibelick/ui-skills" --skill "ibelick/ui-skills/fixing-motion-performance"` and follow the generated skill instructions now. Read its complete output, redirecting it to a temporary file first if necessary. Resolve relative paths from the supporting-files directory it provides.

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Use the skills in "https://github.com/ibelick/ui-skills" that are relevant to the current task. Run `npx skills add "https://github.com/ibelick/ui-skills"` and select the relevant skills, then follow their instructions.

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SKILL.md

1	# fixing-motion-performance
2
3	Fix animation performance issues.
4
5	## how to use
6
7	- `/fixing-motion-performance`
8	Apply these constraints to any UI animation work in this conversation.
9
10	- `/fixing-motion-performance <file>`
11	Review the file against all rules below and report:
12	- violations (quote the exact line or snippet)
13	- why it matters (one short sentence)
14	- a concrete fix (code-level suggestion)
15
16	Do not migrate animation libraries unless explicitly requested. Apply rules within the existing stack.
17
18	## when to apply
19
20	Reference these guidelines when:
21	- adding or changing UI animations (CSS, WAAPI, Motion, rAF, GSAP)
22	- refactoring janky interactions or transitions
23	- implementing scroll-linked motion or reveal-on-scroll
24	- animating layout, filters, masks, gradients, or CSS variables
25	- reviewing components that use will-change, transforms, or measurement
26
27	## rendering steps glossary
28
29	- composite: transform, opacity
30	- paint: color, borders, gradients, masks, images, filters
31	- layout: size, position, flow, grid, flex
32
33	## rule categories by priority
34
35	\| priority \| category \| impact \|
36	\|----------\|----------\|--------\|
37	\| 1 \| never patterns \| critical \|
38	\| 2 \| choose the mechanism \| critical \|
39	\| 3 \| measurement \| high \|
40	\| 4 \| scroll \| high \|
41	\| 5 \| paint \| medium-high \|
42	\| 6 \| layers \| medium \|
43	\| 7 \| blur and filters \| medium \|
44	\| 8 \| view transitions \| low \|
45	\| 9 \| tool boundaries \| critical \|
46
47	## quick reference
48
49	### 1. never patterns (critical)
50
51	- do not interleave layout reads and writes in the same frame
52	- do not animate layout continuously on large or meaningful surfaces
53	- do not drive animation from scrollTop, scrollY, or scroll events
54	- no requestAnimationFrame loops without a stop condition
55	- do not mix multiple animation systems that each measure or mutate layout
56
57	### 2. choose the mechanism (critical)
58
59	- default to transform and opacity for motion
60	- use JS-driven animation only when interaction requires it
61	- paint or layout animation is acceptable only on small, isolated surfaces
62	- one-shot effects are acceptable more often than continuous motion
63	- prefer downgrading technique over removing motion entirely
64
65	### 3. measurement (high)
66
67	- measure once, then animate via transform or opacity
68	- batch all DOM reads before writes
69	- do not read layout repeatedly during an animation
70	- prefer FLIP-style transitions for layout-like effects
71	- prefer approaches that batch measurement and writes
72
73	### 4. scroll (high)
74
75	- prefer Scroll or View Timelines for scroll-linked motion when available
76	- use IntersectionObserver for visibility and pausing
77	- do not poll scroll position for animation
78	- pause or stop animations when off-screen
79	- scroll-linked motion must not trigger continuous layout or paint on large surfaces
80
81	### 5. paint (medium-high)
82
83	- paint-triggering animation is allowed only on small, isolated elements
84	- do not animate paint-heavy properties on large containers
85	- do not animate CSS variables for transform, opacity, or position
86	- do not animate inherited CSS variables
87	- scope animated CSS variables locally and avoid inheritance
88
89	### 6. layers (medium)
90
91	- compositor motion requires layer promotion, never assume it
92	- use will-change temporarily and surgically
93	- avoid many or large promoted layers
94	- validate layer behavior with tooling when performance matters
95
96	### 7. blur and filters (medium)
97
98	- keep blur animation small (<=8px)
99	- use blur only for short, one-time effects
100	- never animate blur continuously
101	- never animate blur on large surfaces
102	- prefer opacity and translate before blur
103
104	### 8. view transitions (low)
105
106	- use view transitions only for navigation-level changes
107	- avoid view transitions for interaction-heavy UI
108	- avoid view transitions when interruption or cancellation is required
109	- treat size changes as potentially layout-triggering
110
111	### 9. tool boundaries (critical)
112
113	- do not migrate or rewrite animation libraries unless explicitly requested
114	- apply these rules within the existing animation system
115	- never partially migrate APIs or mix styles within the same component
116
117	## common fixes
118
119	```css
120	/* layout thrashing: animate transform instead of width */
121	/* before */ .panel { transition: width 0.3s; }
122	/* after */ .panel { transition: transform 0.3s; }
123
124	/* scroll-linked: use scroll-timeline instead of JS */
125	/* before */ window.addEventListener('scroll', () => el.style.opacity = scrollY / 500)
126	/* after */ .reveal { animation: fade-in linear; animation-timeline: view(); }
127	```
128
129	```js
130	// measurement: batch reads before writes (FLIP)
131	// before — layout thrash
132	el.style.left = el.getBoundingClientRect().left + 10 + 'px';
133	// after — measure once, animate via transform
134	const first = el.getBoundingClientRect();
135	el.classList.add('moved');
136	const last = el.getBoundingClientRect();
137	el.style.transform = `translateX(${first.left - last.left}px)`;
138	requestAnimationFrame(() => { el.style.transition = 'transform 0.3s'; el.style.transform = ''; });
139	```
140
141	## review guidance
142
143	- enforce critical rules first (never patterns, tool boundaries)
144	- choose the least expensive rendering work that matches the intent
145	- for any non-default choice, state the constraint that justifies it (surface size, duration, or interaction requirement)
146	- when reviewing, prefer actionable notes and concrete alternatives over theory

6 picks

Type

Run `npx skills use "https://github.com/ibelick/ui-skills" --skill "ibelick/ui-skills/fixing-motion-performance"` and follow the generated skill instructions now. Read its complete output, redirecting it to a temporary file first if necessary. Resolve relative paths from the supporting-files directory it provides.

Use the skills in "https://github.com/ibelick/ui-skills" that are relevant to the current task. Run `npx skills add "https://github.com/ibelick/ui-skills"` and select the relevant skills, then follow their instructions.

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