When there is a thick red rectangle around REPL, I pressed the stop button on the menu and observed increased CPU consumption. It seemed obvious from the information of task manager and increased fan sound.

I am also having this issue and have attached log files that I have from my session, although they look uninformative.

Computer Specification: Java Version 1.7.0_07 from Oracle Corporation Windows 7 Enterprise SP1 Intel Core 2 e8400 4.00 gb RAM Computer is located on IU campus in Psychology Building Computer lab

Also able to reproduce on my home computer running Windows 7 Ultimate with an i5 2500k and 4gb RAM

Steps to reproduce: Open wombat. Press enter in REPL - Execute window with no input. Stop and confirm stop. After confirming stop, check task manager processes, javaw.exe takes 50% of CPU usage with ~48 mb of memory used Force quit javaw.exe petite.exe persists for a few seconds, at ~50% of cpu usage and high memory usage (up to 4 gb)

There are some cases which leave zombie Petite processes which are only killed when Wombat exits. I'll look into it.

https://github.com/jpverkamp/wombat-ide/issues/22