We know Esprima is used to validate scripts on upload (makes sense), and also at runtime. The runtime check helps if the rules for what is safe in scripts change -- for example, when comments outside functions were disallowed, esprima was able to catch scripts uploaded under old rules that fail under new. This is GREAT, but esprima is slow and parse is an issue. Reducing Esprima would likely speed parse time and save a lot of server work. My proposal: 1) set a 'rule version' on every script's db entry, initially to 0 2) set a 'rule version' in code, initially to 1 3) on upload, after esprima check, set the db entry's rule version to whatever the code version is 4) on run, if saved version doesn't match code version, run esprima. If saved version does match code version, skip esprima. After a successful esprima run, update saved version 5) any time parse rules change, increment code's version. In effect then: you'd still get esprima every upload (good). And also, you'd get it first run of a script after any rule change (also good). But if it passes after a rule change, that script never will need to be run through esprima again until either the script changes (in which case it'll get run at #up) or the rules do (in which case the bumped code version will trigger a re-check next run). That should drastically cut down on runtime esprima usage without losing the very important ability to force a recheck at runtime **if needed**.