mame2003-plus: decompressed rom support?

Installed latest stable retroarch mame2003-plus on my 3ds xl, and while it runs really well, rom loading/decompressing time is killing me - >1min to decompress/load 1942.zip. Is there any way to make retroarch handle a decompressed romset - one complete rom per directory?

eg: /roms: /1942: foo1.bin foo2.bin … foo10.bin /1943: bar1.bin bar2.bin … bar10.bin

When i try to “load content” and open the /rom/1942 directory, instead of loading its content, it opens it for scanning. Any idea how can i solve it?

Not that I know of, no. Only zips.