PC vs PLC

hi group


i´ve been using cncpro, m5, and flashcut for some time now, and i
have noticed short and random hick-ups. could this be a windows issue
rather than the controler sw? i heard that some harddrives and
motherboards sometimes sort of calibrates/updates itself for a
millisecond or so thus causing a flickering in the pulsetrain. is
this true or could it be some hidden backgroundprog that disturbs the
smoothness? does ctrl+alt+del show everything that is active? does
anyone know how to tune xp into an optimal cnc-controler?

js