An update. The above scenario happens when I modify a class which is an abstract base class for a lot of Spring beans. And "JVM is stuck" is not correct. It actually starts responding. But after more than 1 minute of high CPU usage.
If I modify a "lighter" class, e.g. a normal Spring bean w/o subclasses, Eclipse doesn't show the "Error" popup w/ timeout. The "swap" still generates high CPU usage, but for maybe 10 seconds. But anyway, this is still a lot, compared to how it used to work.
I tried w/ 2 versions of DCEVM. 11.0.1+8, 11.0.10+2