The inline edit feature for Behaviours can cause a large number of redundant requests to the validators.json endpoint when viewing issues via a JQL search (e.g. <jira base url>/issues/KEY-123?jql= where KEY-123 is an issue key). Because cacheing is disabled, each request has to complete. This happens every time you use the arrows to navigate the results up or down (or use the j/k keyboard shortcuts).
If you disable the ScriptRunner module Behaviour inline edit issue assets (bh-inlineEditPluginResources), browser CPU usage goes down by about half during issue switching and the requests go away. The performance impact is worse when there are larger numbers of issues in the queue.