Here is what appears to be a repeatable bug with the Jan-19 beta.

Given the attached file, select the bottom surface (that embeds the text Otterman), then press the delete key. 1 processor utilization goes to about 80%, and the program becomes unresponsive for at least a couple of minutes. Then I get impatient and use the task manager to abort the process.

Is this a genuine bug, or just a hard problem that needs patience?

For my next trick, I will attempt to separate the piece into surfaces and get rid of the bottom that way.