I don't have a source other than that I develop plugins for IntelliJ professionally, but it's definitely true that performance is generally not a focus earlier in EAP cycles. I think they mention it when you download an EAP release.

I can't find a source to my claim. Just now downloaded webstorm 2022.2.3 stable and webstorm 2022.3 EAP to compare, but they seem to behave similar in cpu. Every now and then in the EAP in the activity monitor a "diagnostics dumper" pops up, but only for a brief moment. Maybe they improved it a lot. I remember complaining about EAP performance a long time ago and remembered an answer to expect a few more cpu usage from an EAP (the diff was not as stark as 100% though, it was more like 20% EAP vs 5% stable).

I mean please don't judge the CPU profile of an EAP to the final product.