This is a very old problem, and isn't a bug as it's how much can Construct keep in 1 event_sheet, and your pc reading all that (having a SSD assigned to Construct caching and processing might help a bit).
Cheap solution to this problem i found a long time ago, since i started using Construct 2, don't keep all events in 1 event sheet, also don't have more than 10-12 actions in 1 condition(you can add blank sub_conditions instead of keeping all actions in the main condition - for some reason, it kinda clears the heaviness)
if you have different events and conditions for different characters hud etc splice them up into other event_sheets and use include, separate all events into other event_sheets where you can, and use the include.
reuse code either by using functions or families, so you don't have to repeat the same code by copy pasting it and fire it 100 times from 10 different conditions when can actually be done once and run for all the objects that apply to that code.
having groups only lowers the usage when u close them, but is not gonna solve the issue, if u start searching for a line of code as an example ... it will unlock everything basically and crash Construct.
this is kinda the same issue as with any software, if you overload the screen or event sheet in screen it will eventually crash, you can see wordpress and unity even, and other platforms have the same issue, they can handle the stuff, but to a surtain limit, you have to organize.
when i started with Construct i was creating like 2 conditions and each condition would had like 20 30 actions, and wondering what is going on... because the game was relatively small... but u gotta remember, that each action has to check if condition is ok, the more u add the more u check that condition, and the system has to do all that in a tick, cause under it there are 300 more lines....