docs: reorganize into en/ru and add English translation

docs/en/architecture/02-performance.md

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+# Performance Analysis
+
+Measurements with the `--perf` flag on `desktop.glbc`.
+
+## Measurement Results
+
+**Steady state** (no events, idle):
+
+```
+VDOM: 6.6ms | Style: 0.3ms | Render: 7.2ms | Total: 14.1ms
+```
+
+**Under events** (slider drag, peak values):
+
+```
+VDOM: 17.4ms | Style: 0.8ms | Render: 15.2ms | Total: 33.5ms ⚠️
+```
+
+**60 FPS frame budget: 16ms.** At idle we fit (14ms), under events — not (up to 33ms).
+
+## Bottleneck Analysis
+
+### Style matching — NOT a bottleneck (0.3-0.8ms)
+
+Style matching takes less than 1ms even at peak. This is the result of:
+- **Phase 4** (StyleIndex) — O(K) instead of O(N×M)
+- **Phase 8** (StyleCache) — computed style memoization
+
+### VDOM eval — main consumer (6-17ms)
+
+At idle ~6.6ms — a full traversal of the Element tree. Under events up to 17ms:
+- `evaluate_vdom_incr` recalculates dirty elements (Phase 3)
+- Each event can dirty entire subtrees
+- Internally: `resolve_string`, `resolve_prop`, `compute_cached`, recursive traversal
+
+### Render — second consumer (7-15ms)
+
+**This is where the main optimization headroom lies.** `render_element` creates ALL Iced widgets
+from scratch every frame, even if the Element hasn't changed. Iced then diffs the new tree
+against the old one — but the tree construction itself costs ~7ms.
+
+### Scenario: slider
+
+1. `SliderChanged` → `age` and `volume_level` change
+2. `tracker.on_variable_changed` → dirty_set for dependent elements
+3. `evaluate_vdom_incr` recalculates dirty elements and their children
+4. `view()` → `render_element` for ALL elements (full re-render)
+5. Result: VDOM 13ms + Render 14ms = 27ms — frame drop
+
+The first few frames after an event are the heaviest (VDOM ~13ms), then
+stabilize (~7ms) as dirty_set gradually clears.
+
+## Recommendations
+
+1. **Phase 9.3 — widget cache** — would reduce Render from 7ms to ~0ms for unchanged
+   elements. If 1 out of 50 elements changes, only that one needs re-rendering.
+   This would lower total time from 14ms to ~7ms at idle.
+
+2. **Phase 1 — Value enum in styles** — `ComputedStyle::compute()` and `parse_*()`
+   take `&str` and parse each property. Passing `&Value` instead would skip parsing.
+   Potentially speeds up both style matching and VDOM eval.
+
+3. **Phase 2 — InternedStr** — string comparisons (`type_name == "Button"`,
+   `key == "padding-top"`) happen thousands of times per frame. Replacing with u32
+   comparison would give 1.5-2× in VDOM and render paths.
+
+4. **Phase 0.3 — flamegraph** — confirm hypotheses with profiler measurements
+   (`perf record`) before investing in optimization.