Same here, using a UHS-1/80 MB/s SDHC card (SanDisk), Snes ROMs take forever to load, and there's only what, 84 files in the folder, but Genesis, NES, etc load almost instantly.
I've tried three different SD cards, all with different read speeds, so it has to be more than just "our SD cards" that are playing a factor in this. Why do some cores load folders instantly with the same no. of files, but other cores take 30 seconds to load a folder with less files in it? Makes no sense.
An 80 MB/s card should not take the same amount of time to load a ROM folder than a 30 MB/s SD card, just saying
![tongue :P :P](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
As I recall the Wii port had a similar issue but resolved itself over time. I'd report it on GitHub, but isn't worth it as it'll be fixed. Some people have the issue, others don't, much like the Haxchi HBL forwarder working with RPX apps.
Granted, it's not as bad as when the first build came out, Snes took 60 seconds to load a ROM folder instead of 30.