The quantified events of Quartz clocks sometimes inaccurate

[Season02]

I found the Quartz clock`s quantization event inaccurate
I subscribed eight note event,here is my blueprint:

I use this section to calcuate the time between two EightNote:

When the game starts I got this output:

4/4 beat, BPM60, the time interval should be 0.5s, but through the printed log found that the time interval is inaccurate,not stable 0.5s
Why the time interval between two eighth notes sometimes inaccurate?

[Season02]

I know this caused by game fresh rate (30fps),but I really need get event at correct beat time,the latency 0.033333s was too long, Is there a solution？

[Season02]

This was the solution, question closed. Music Timing System - #16 by PenguinTD