Performance issue in Internet Explorer 11

[Hypnobrew]

Tested in 2.1.2 and 2.7.1.

Hi

I have a performance issue with the the javascript client for Launch Darkly in IE 11 (Most likely earlier versions as well).
When using the client in pages with a fair amount of dom elements, reloading the page several times increases the memory usage in IE11.
Removing the LD client removes this behavior.

Maybe the cause is that the eventlisteners in index.js are not removed, which blocks the GC to clean references to the window object correctly? In that case the cleanup could be done in beforeunload.

On a page with less amount of dom elements the effect is much smaller but still noticeable.
Chrome, FireFox and Edge have no issues.

Any help is much appreciated!

[Hypnobrew]

If this is a problem caused by the explanation above and it affects others as well, I can create a fix and make a PR.

[eli-darkly]

If you're in IE11 then I would be very surprised if event listeners could persist after a page is reloaded. I've seen some reports that leaks like that are possible in older browsers, such as here, but not in anything more recent. However, if you're able to reproduce this problem consistently, then it could be worth trying the approach you suggested and seeing if it does in fact make a difference. We'd have no problem with making this change anyway to be on the safe side, but I'd like to know whether it does fix your problem or whether there may also be something else going on.

[Hypnobrew]

I will do some further testing and see if I can reproduce the issue with a PoC.
Thanks!

[Hypnobrew]

Hi

Made some further investigations and found out it is not the LD client causing the problem. The root cause is somewhere in our own code and the LD client performance problem was just a symptom.

Closing this issue!

[eli-darkly]

Thanks for the update!