What events or conditions are heavy on memory

[Simflare]

I have one overall question and a few specific points. I'm looking at optimization and curious what events are potentially heavy on memory usage and should be either avoided or used with caution, particularly for mobile apps.
I know fastloops are heavy on memory usage.

1. Are 'For Each' loops faster than fastloops?
2. Are 'For Each' loops heavy on memory?
3. Is the 'Always' event heavy on memory (I've heard that it is)?
4. What other events are potentially heavy on memory and should be handled with care?

Bear in mind I'm asking in light of maximizing optimization if one had to squeeze every ounce of performance out.
Thanks
Simflare

[Ryan]

1) Yes, if you've got multiple active objects to loop through. Object selection is sped up exponentially.

2) Not as heavy as fast loops, by memory I think you mean cpu processing power, because the object selection wouldn't actually keep the object in memory after it's done what it needs to.

3) You shouldn't use lots of 'always' events, not that it's heavy on memory but that it happens every frame, thats 50 times a second by default. You can optimise by sharing your cpu-heavy events across many frames. Got 60 units that need to follow AI? Rather than have them think every frame, have 20 think on frame 1, 20 think on frame 2, and 20 think on frame 3, then repeat. Your AI doesn't need to have faster-than-human reflexes, the usual human response is 200-400 milliseconds, so a few frames of lag is fine.

4) Don't be afraid to use fast loops in conjunction with arrays, lists, or other non-active things you need to iterate through. Always put a fast loop in it's own group and run:
Activate group Myloop
run loop "Myloop" x amount of times
Deactivate group Myloop.

MMF actually needs to do a search on all fast loops to find the right one, but it doesn't search deactivated groups. Not sure if this applies to For Each loops.

[Perry]

If an event doesn't need an "Always" , you can replace it with i.e. "Run only once" or "Start of Frame"
This will reduce a little bit of memory since it's not "Always" scanning for the specific event.

[Pineapple]

Checking collision is probably the biggest cause of slowdowns.

[rubes]

Ryan, thanks for #3, that's a great way to think about things

3) You shouldn't use lots of 'always' events, not that it's heavy on memory but that it happens every frame, thats 50 times a second by default. You can optimise by sharing your cpu-heavy events across many frames. Got 60 units that need to follow AI? Rather than have them think every frame, have 20 think on frame 1, 20 think on frame 2, and 20 think on frame 3, then repeat. Your AI doesn't need to have faster-than-human reflexes, the usual human response is 200-400 milliseconds, so a few frames of lag is fine.

[Simflare]

1)

3) You shouldn't use lots of 'always' events, not that it's heavy on memory but that it happens every frame, thats 50 times a second by default. You can optimise by sharing your cpu-heavy events across many frames. Got 60 units that need to follow AI? Rather than have them think every frame, have 20 think on frame 1, 20 think on frame 2, and 20 think on frame 3, then repeat. Your AI doesn't need to have faster-than-human reflexes, the usual human response is 200-400 milliseconds, so a few frames of lag is fine.

Thanks for your response, Ryan. How would one separate that over several frames? I understand the logic, but off the top of my head I can't think how I could program it in to events.

If an event doesn't need an "Always" , you can replace it with i.e. "Run only once" or "Start of Frame"
This will reduce a little bit of memory since it's not "Always" scanning for the specific event.

Good point Perry. I do try and find ways to replace "Always" with other events, usually with "If number of objects > 0"

[Ryan]

Create global value currentframe

Always
> spread value 0 in enemy alterable value 'ID'
> set currentframe to currentframe + 1
> run fast loop 'AI' (Number of Enemies/3) times

On loop AI
+ ID of enemy = loopindex("AI")+((currentframe mod 3)*(Number of Enemies/3))
> Do AI for this enemy

Look up information for the Mod function, there's plenty of info on google about it and this forum. I added extra brackets for comprehension purposes, some can be removed due to order of operations.

You could also replace the AI loop with a ForEach, maybe you could experiment and see which is faster. How much performance boost you get from this method really depends on how complex your AI is.

[Simflare]

Ah ok cool thanks.

Here's another question about optimization, and this one is about scoping.

Say I have 2 different events to control the hero movement. Event 1 is "walking", Event 2 is "running".

If I want to check if the hero is running, I could either check if:

1. the run key is being pressed, or
2. alterable value "running" is set to 1, aka true

So in other words, I'm either checking to see if a key is being held down, or if a variable is set to a certain value.

Which would be quicker to check for, and would either be better in terms of overall optimization? Purely a theoretical debate, not necessarily for this particular application.
Thanks

[Ryan]

I would say the 2nd is slightly worse because you're adding another level of complexity

If run key is pressed
> Set running to 1

If running = 1
> Do something

Where you could do:

If run key is pressed
> Do something

But lets say you want to do lots of things when running:

Yes you could do:
If run key is pressed
> Do something

If run key is pressed
+ Jump key is pressed
> Do something else

Or instead you could do:

If run key is pressed
> Activate group 'Running'

Group Running {
Always
- Do something
If jump key is pressed
- Do something else
If attack key is pressed
- Do something awesome
Always
- Deactivate group Running
}

It's a lot more optimised than checking the same conditions over and over again.