Hello eepjr24
In order to diagnostic the memory issue:
- restart Gimp before each very big bumpmapping
 
- make a clean reboot as you wrote yourself
 
- Gimp menu Windows > Dockable Dialogs > Dashboard as suggested by rich2005
 
- Gimp menu Windows > Dockable Dialogs > Error Console
 
How to run Gimp for debugging purpose?
Right-click Windows 
Start > contextually menu 
Windows Powershell.
Add or 
not the following 
Command Line Arguments after the Gimp executable as 
optional parameters:
Code:
. "C:\Program Files\GIMP 2\bin\gimp-2.10.exe" --console-messages --stack-trace-mode=always --no-shm
 
  ^ Don't forget the Powershell 
dot operator at the very beginning of the command.  
 
More precisely, use or 
not, --step-by-step--, the following Command Line Arguments:
- --console-messages: Do not popup dialog boxes on errors or warnings. Print the messages on the console instead.
 
- --stack-trace-mode=always: Debug in case of a crash
 
- --no-shm: Do not use shared memory between GIMP and plugins
 
- --no-cpu-accel: Do not use special CPU acceleration functions. Useful for finding or disabling buggy accelerated hardware or functions.
 
Powershell starts a new black console that will display a lot of GECL warnings even when it works.
At the end of session, after you quit Gimp, you are invited to close the black console:
Code:
(Type any character to close this window)
 
Before entering 
any character, save valuable warning messages by 
Ctrl+
C to help to diagnostic the debugging session.
Paste them by 
Ctrl+
V in this forum.
For example even if it is 
unrelated with the subject:
Code:
(gimp-2.10.exe:9852): GLib-GIO-WARNING **: 12:50:25.480: Unexpectedly, UWP app `Evernote.Evernote_10.22.3.0_x86__q4d96b2w5wcc2'
(AUMId `Evernote.Evernote_q4d96b2w5wcc2!Evernote') supports 1 extensions but has no verbs
GIMP-Error: Unable to run plug-in "liblqr-1-0.dll"
(C:\Users\YourWindowsUserName\AppData\Roaming\GIMP\2.10\plug-ins\liblqr-1-0.dll)
Failed to execute child process (Exec format error)
 
Regards.