# Is croct.evaluate fast enough to call on every route change?

Asked by andrei.s on 2026-05-05. Tags: performance, cql, evaluation, spa.

SPA, classifieds site, high navigation frequency. I gate a UI element behind
this on every client-side route change:

```js
croct.evaluate("user is returning and session's stats' pageviews > 3")
```

Works fine. Question is whether calling it per navigation is an intended pattern
or an abuse I will pay for at scale. Alternative would be caching the result per
session in memory.

average user does 15-20 navigations per session here.

## 1 answer

### Answer from samw (2026-05-05)

Per-navigation is the intended pattern, not an abuse. CQL evaluation targets
under 20ms and the whole API is built for real-time per-interaction use, so
15-20 calls per session is squarely what it is designed for.

More importantly, your specific condition is one you should NOT cache. It
contains `session's stats' pageviews`, which grows as the user browses. Cache
the result on navigation 2 and the user who crosses the threshold on
navigation 5 never flips. Real-time evaluation is the feature, caching it
defeats the point. Only cache conditions whose inputs genuinely cannot change
mid-session.

Two hygiene points for high-frequency calls:

```js
croct.evaluate("user is returning and session's stats' pageviews > 3")
    .catch(() => false);
```

Always attach the `.catch` so a network hiccup degrades to the default UI
instead of an unhandled rejection in your router. And keep queries within the
1-500 character limit, which yours is nowhere near, but it matters if you
start composing bigger conditions dynamically.

#### Reply from andrei.s (2026-05-06)

The pageviews clause is exactly what I would have gotten wrong, a cached
stale false. Keeping it per navigation with the catch.