[MrNice]

At first I had the issue with #0714 then I installed the #0726.
So this is older but I don't know from when.

Install the Leopold OE updater addon and find the first build with the problem. You can probably do this in fifteen minutes. With this information you are much more likely to get a fix.

I did some tests, all with the same process, no setup change:
Directory in SD with inside 7 audio files (see post #276)
Install new build with add-on, go to the directory in the SD, move the selection on the file, wait 15 seconds, read value from ssh/top, move to the next file.
Results:
Build | low CPU% (good files) | High CPU% (bad files)
#19852 (date: 22/Dec) | 15 | 66
#19882 (date: 01/Jan) | 15 | 65
#20173 (date: 01/Feb) | 15 | 69
#0301 | 15 | 70
#0401 | 67 | 69
#0501 | 66 | 81
#0601 | 59 | 62
#0701 | 64 | 64
#0401 | 63 | 66 (again to be sure)
#0726 | 09 | 95 (again to be sure)

My conclusion as a user:
2 type of files
Builds #0501 and #0726 have higher values.

I'll try to find the last change between #0701 and #0726