Combat Log Event Timing

[&res]

Hello. I'm new here and new to ui customization as well. And this is my first post here I'm working on my first simple addon and I got a question about combat log event timing.

The addon basically tries to predict when a next 'tick' of a channeled spell lands. The event I monitor is "COMBAT_LOG_EVENT_UNFILTERED". On event type "SPELL_AURA_APPLIED" I get channeling duration with select(6, UnitBuff("player", spellName)) and divide it with total number of ticks to get the time for one tick. Now when on event type "SPELL_PERIODIC_DAMAGE" I compare the computed tick time with the actual time (by using GetTime() in appropriate places) the difference seems to be in range +- 0.3 seconds. When a tick takes around 2.5 sec then it is quite a lot imho.

Is it because of latency (was around 75ms at the time I tested) or do the combat log events just land inaccurately like this? Or are there some other ways more accurate than combat log to detect when periodic damage (or any spell/action really) lands?

Thank you.