This has been addressed previously in the forum in a number of threads.
Assuming you are using Samba from a PC to transfer files, are you using Ethernet? Some here also use FTP as being faster than Android file managers like ES. Suggest you read the FAQ?
The absolute fastest way for large files is to plug the Q10 Pro into the PC directly using the rear USB port. Files transfer at USB 3.0 speeds

I have full Blu-ray remux files of 40Gb+ in size and this works great using Windows Explorer.
You will also find the Samba Optimisation Patch works well in speeding up file transfers: http://www.futeko.com/newforum/index.php?topic=1479.0