This is a long time issue. It has remained across a few versions of EFL and Terminology. I thought it was Firefox. But I have experienced this without Firefox and ~15 Terminology windows. I do not think its Terminology, but deeper issues in EFL which terminology triggers. Though could be bug in Terminology code.
It takes some time to trigger. Seems to happen when I am deep in work with many terminals, and history in each. I have on idea on a trigger or cause. I cannot replicate. I just know it continues to occur and is very frustrating. I must restart E and resume all terminals and work.
Not sure if anything can be done, given the vagueness of this report. Mostly a issue tracker, for when ever I no longer experience this to close. Till then something for others to at least be aware of in case others run into it. Maybe someday I can look to debug.
I built EFL with debugging symbols, and it blew up E big time. Many things became non functional, My pinentry-efl would not launch, many things broke. Lots of output on unable to lock. I can see about doing that again and opening a bug on such. At this time given those issues I cannot provide useful crash output.
At this time nothing else triggers the issue other than Terminology. Though I can replicate a oom via ecrire and large files. Not sure if related. I know I have experiened 100% CPU with EFM, but that seems to have been resolved. Though I do not use EFM much so it may still occur, just has not for me in some time due to minimal usage.