Surface Pro 3 and MicroSDXC

[olimjj]

Is there a caching program for the SD card?
For example, 500MB cache of the SD card on the SSD. Something like how SSHD works. That would hugely boost the speed.
I tried PrimoCache but it crashed the whole SP3 every few minutes.

If your talking about Write Caching on SD card you can implement it directly:
In File Explorer, Select the SD card, right click to Properties, Hardware, SDXC card, Properties, Change Settings, Policies, Write Caching Policy