when 128k is not enough

[richard]

On the other hand, doesn't that make for unpredicatble latency, ie one interrupt it needs to save 5 variables, next interrupt it needs to save 10? I'm asking, not arguing by the way ;-)

turns out to be quite true but still near 3 times faster on average

mikroc latency for the previous example ranges from 16-21uS
pbp is not rock steady either there I a 1-2 uS variation