Quick answer: Unity domain reload dragging editor iteration to a crawl? Disable Domain Reload on Enter Play Mode and clear static state manually - cuts iteration time by 10-100x.

Press play. 90 seconds of Reloading domain later, you can finally test the one-line change.

Disable in Enter Play Mode

Edit > Project Settings > Editor > Enter Play Mode Settings. Uncheck Reload Domain. Play mode now skips the reload.

Reset static state explicitly

[RuntimeInitializeOnLoadMethod(
  RuntimeInitializeLoadType.SubsystemRegistration)]
static void Reset() { ... }

Without domain reload, static fields persist across play sessions. Reset them yourself in this callback.

Audit static state

The Console will warn about static field not reset for the first session. Fix each warning; subsequent plays will be clean.

“Domain reload is the slow path. Skipping it requires you to do its job for it.”

Make 'static reset' a code review checklist item. Once a project disables domain reload, every new singleton becomes a potential cross-play-mode bug.