Ever since I switched to Arch Linux I’ve had absolutely terrible SMB performance. I tried tweaking the SMB settings on the client and server with no success. Windows had no problems so it was clearly a client side issue. Basically the problem is caused by the TCP read/write buffers not being large enough. If the buffers are too small you will end up with 50MB/s read/write speeds when they should be 90MB/s+.
Reboot or apply the settings using the
sysctl command. You should now have a nice performance boost with SMB shares!