Process Lasso does not seem to take any action to estrain overly active processes. What is going on?
By default, Process Lasso excludes the foreground process (the one that has keyboard and mouse focus). You should click to another window to allow Process Lasso to restrain the process. Alternatively, you can turn off exclusion of foreground processes. The occasional restraint of foreground processes won’t hurt anything since any active background processes will also be restrained at the same time. Of course, by restraint we simply mean temporarily lower the priority class, not any sort of actual limit on CPU usage (see ProBalance docs).