Lightroom Classic 11.4 very slow to export.

I upgraded to 11.4 and the exporting was at least 2-3x slower.  Sporadic starting/stopping with the progress bar.  On Windows 10, fast machine with SSD with plenty of disk space.  This was with the GPU setting set to Auto or Off, no difference. 

I downgraded to 11.3.1 and it's back to normal without this issue.

"Exporting 500 RAW to JPG photos would take a couple of minutes"

To build on DdeGannes' reply, that seems unusually fast. 

Do a simple performance measurement: Select 50 raws. Using the stopwatch on your phone, time an export of those 50 raws, with Preferences > Performance > Use Graphics Processor = Custom,

a) In LR 11.4 with Use GPU for Export turned off 

b) In LR 11.4 with Use GPU for Export turned on

c) In LR 11.3.1.

Do three runs for each of a, b, and c, and take the middle time of the three runs.

With my Macbook Pro (2019, 8-core Intel i9, AMD Radeon Pro Vega 20 - 4 GB),

a) 1.8 secs/photo

b) 1.5 secs/photo

c) 1.8 secs/photo

My GPU has only 4 GB, half of the minimum 8 GB LR wants to see before it defaults Use GPU for Export to on, which probably explains why the speed I'm seeing from the use of the GPU is modest compared to what others report. 

And I don't observe any difference in speed between LR 11.3.1 and 11.4.

Provide info on your system resources including Disk drives involved in the process, including full disk size and free space available. I would hazard a guess 1 to 2 seconds per image, render the raw image apply all edits and write to disk.

500 images 8 to 15 minutes.

You say prior experience was much faster, then I suspect your free disk space has been reduced over time and is affecting the process. If the disk involved has less than 20-25% free it will begin to affect performance.