WowAce

What version of Grid2  are you using (Version is displayed in General/About Tab) ?

2.9.22

What game client version, classic or retail, windows or mac and language are you using ?

TBC Anniversay

What steps will reproduce the problem?

Setting health update frequency to 'Instant' and buffing Power Word: Fortitude on yourself

  
Did you try having Grid2 as the only enabled addon and everything else disabled?

Yes

Was it working in a previous version? If yes, which was the last good one?

Unknown

Do you have an error log of what happened? If you don't see any errors, make sure that error reporting is enabled (`/console scriptErrors 1`) or install [BugSack](https://mods.curse.com/addons/wow/BugSack).

Please provide any additional information below.

When setting the health update to 'Instant' and buffing myself with Fortitude, it will take over 1.5 secs for the new health deficit to appear on the frame.

Instant method tracks the enemy attacks using the combatlog to predict and display the future health substracting the attack damage from the current health.

In the case of buffs this method is not applicable, and the health is updated at the normal rate, when the game decides to inform addons about the health change.

Thanks for the info. The peculiar thing is that if health update is set to 'Normal', a deficit created by buffing will display immediately.  Its only when 'Instant' is used that the delay occurs. 

This means that the normal health update is faster than the combatlog update (at least for this specific case), so the addon can do little to fix this.

The Instant method works assuming combatlog updates are faster than normal health updates, if this is not the case it has no sense to use this option.