The explanation for this has to do with the nature of Process Tamer and what it is doing.
Process Tamer does not explicitly try to make programs use less of your cpu. What it does is adjust the relative priority of processes, so that if you have one process that is TRYING to use up all your cpu, and there are OTHER processes that are asking for cpu time, Process Tamer can ensure that the OTHER processes operate smoothly and get enough time to run responsively.
What that means is that in a case like the one you are showing, where only 1 process is really competing for the cpu, you shouldn't see very much of a difference (windows GUI controls, start menu, etc. may respond a bit faster).
It is only when you have a second program that you want to use where you should see the real difference. With PT taming your terminal.exe application and setting it to low priority, your OTHER apps should now run more smoothly.
So for example if you run another process that needs a substantial amount of cpu time simultaneously with this terminal.exe which is currently alone using 90% of your cpu, THEN you should see that 90% drop lower when PT has lowered its priority, compared to if its priority it normal.
Does that make sense?