TM4C129XNCZAD: How to trigger an instant reset

Part Number: TM4C129XNCZAD

I still have the problem of a slow CPU on some boards, as described in this thread:

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/1373456/tm4c129xnczad-help-when-i-power-up-my-device-without-the-jtag-cable-connected-the-display-becomes-sluggish/5246105#5246105

I have determined that if I just cause a CPU reset after the system is running, it comes up in "fast mode" with no latency or sluggish response.  Right now I'm doing it by putting it into an infinite loop and letting the watchdog reset the system.  Is there a way to trigger an instant reset, like by issuing a bad instruction?

Also, does the fact that a reset puts it in the right mode provide any new information that would help determine what the original issue is?

Thanks very much.