I know this issue will be very generic, but...
I'm seeing a perceivable performance degradation in latest Greclipse when working on large Groovy sources (I'm using Greclipse 4.7.0.v202209190834-e2206).
Right now I'm working with a ~3000 rows JUnit test class and:

• any content assist request takes from 2 to 5 seconds and more; if I disable non-blocking completion, it will trigger the UI freeze monitor warning or even the popup dialog that says that the Groovy content failed because it took too much time to complete; enabling non-blocking completion improves the perception a bit, but it still takes a lot of time
• saving requires almost 10 seconds, probably due to formatting action on save

Yes, I don't have a bleeding edge system (it's a 4th generation Intel Core i5 processor with 16 GB of RAM), but still the difference compared to working with Java sources is huge.