On the mailing list I wrote down my test results for en- and decrypting files (1-10 GB) with GnuPG and Gpg4win/Kleopatra. The encryption always ran with compression. Kleopatra needed more than 11 minutes to encrypt a file that is 10 GB big. Today I tested the encryption again but this time I added
to gpg.conf (I also tried to add bzip2-compress-level 0 and then only compress-algo uncompressed because Bernhard was suggesting that in the mailing list but it made no difference).