It's not too much for PICBasic at all (remember, this is NOT an interpretive Basic), but might be too much for a 4MHz PIC all depending what it's got to do besides counting 60kHz pulses. This little ditty will show you how far you can go before things start falling apart... use a Double-Trace Scope, monitoring the Input and Output pins, wind the frequency up until the output starts to fall over... you might be surprised...

TRISB=%00000001

InputPin var PortB.0
OutputPin var PortB.7

Start:
Low OutputPin
Loop:
While InputPin=0:Wend
High OutputPin
While InputPin=1:Wend
Low OutputPin
Goto Loop

End

Melanie