Not sure it works that way; the apps are stored on the "system" flash. This isn't RAM and moving apps out of there is only going to change the speed they load/access their app data. The partition they live in is not usable for swap (by default at least. swapping is a very bad idea on media with limited write endurance).

I say change vs speed up or slow down because it depends on how fast the SD card you have inserted is vs the eMMC or raw NAND you have installed internally. You could win, you could lose.

Possibly there are some second order effects if, say, the phone vendor decreed that the internal NAND was "fast enough" and didn't require linux to cache that FS, but the SD card did require caching... that'd then mean the SD card would always be faster. That bit is just speculation though.