Improve jseditor linting performance

Editor assessment

The subject states the goal — js editor linting performance improves — but offers no mechanism: what made linting slow, what was optimized, or how much faster it now runs all stay unknown without the diff. Performance claims are exactly where a body earns its place by describing the bottleneck and the fix. The fix type fits, and the component is named where a scope would sit. No footers appear. Understandable at the intent level only, which keeps the message at acceptable.