Answer:
Yes, the problem might also be caused by RFEM. The preview of RFEM files in Windows Explorer may cause Explorer to react more slowly.
For a possible solution, proceed as follows:
In C:\Program Files\Common Files\Dlubal, rename the ThmShellEx64.dll file to BACKUP-ThmShellEx64.dll.
For the 32-bit version, rename the ThmShellEx.dll file in C:\Program Files (x86)\Common Files\Dlubal to BACKUP-ThmShellEx.dll.
Finally, it is necessary to restart your PC.
