This goes without saying...
Canon's processors are not known to be the most powerful or speedy chips out there, this is why (well partly) that there are so many limitations with video shooting.
Canon needs multicore CPU's or simply double up like on the 1DX II. I think we will definitely be seeing more than one CPU in any mirrorless that has real video specs and/or high speed stills capture.
Can you provide some links as to your assertion?