By default windows may now (2025) launch TOPAS with “normal” priority. This can significantly slow complex refinements down. If you want to launch with high priority you can do this from a cmd prompt or bat file. The syntax from a cmd prompt is:

start “” /high “c:\YOUR-MAIN-TA-DIRECTORY\ta.exe”

Or you can have a file called “TOPAS-High-Priority.bat” in your TOPAS directory with contents:

start “” /high “ta”

VS Code topas-editor will do this by default from release 1.0.16 for TA.exe and topas.exe (academic and commercial, respectively). It doesn't do this for TC.exe.

For TC.exe you can run from a high priority cmd prompt. Open a regular cmd prompt then type the following to get a high priority prompt:

start /high “cmd”

Alternatively you might be able to right-click on the program and “Run as administrator”.