I could not figure out what was going on with my interrupts, all of a sudden the interrupts were taking roughly 10x longer between executions.
this is my clock setup
_clkmode = XTAL1 + PLL16x
_xinfreq = 5_000_000
at boot up CLKFREQ returns 80,000,000 as expected, then after writing to the SD card once it returns 824,195,128 instead. (using fsrw.spin) then it appears to stay put. essentially making all of the waitcnt instructions take a little over 10 times longer.
I've had other strange things with this board as well, for instance if I use SD-MMC_FATEngine instead, then the SD driver will not operate if GPS_IO_mini.spin is used in the same project. I suspect that some resource is being shared not so well but I cannot figure out which one.