Can you experts out there comment on the following ?

RPM Range : 100 to 3600
Pulse/Rev : 1
Period @ 100 RPM : 600,000 microsecond
Period @ 3600 RPM : 16,666 microsecond
Display resolution : 1 RPM
Display accuracy : +/- 0.5% of measured RPM
Display update rate : Once every 1 second
Display type : 4 nos 7-seg. LEDs in multiplexed mode.
Multiplexing : By P89c51RD2 using T0 interrupt every 2ms for each digit.
Period measurement : By PCA timer

Query : In the above setup, is it a good design practice to use MCU for display multiplexing ?

Why I am asking this is, when MCU is measuring period, there are going to be interruptions to the PCA when the mux. interrupt has to be serviced, particularly at low RPMs. Will this affect the accuracy of capture of the period ?

Would it be a better idea to relieve the MCU of the display multiplexing load and use a display driver like 7218 ?

Thanks in advance.

Raghu