Question: GUI not responsive: Do large expressions play a role?

This is about delayed input after executing this file Campo_Médio_spin_7_2_-_Forum_optimize_02.mw

from annother question dealing with very large physics expressions (containing about 100000 exponential functions).

The GUI shows but when I place the cursor in an inputline and type, characters are sometimes displayed with a huge delay (about 20 seconds). This is from time to time, i.e. not always. All on Windows 10, 64 Gb memory and 4 Gb graphic card memory.

Can someone reproduce this?

Has anybody experienced the same (kernel with large expressions & GUI not responsive)?

Anything that I can test or try?

(I had a similar question about file size but this time the file size is small 150 kB and no big plots are made.

Only the kernel has to deal with the large expression. Output displayed on the GUI is negligible.)