...I already deleted the broken build... =(
Are those also placed in Common5? Because that file was definitely way too big.
Oh also the bundles for each character's CSP in Common5 were in fact bigger in my broken version. Not sure if it was enough to matter...but I think any amount is right?
Actually, there is a file size limit for the sel_character_en.pac file, which is, in fact, located on the common5.pac file. In order for the CSS not to crash (and for the game in general to play normally) you will want to avoid going over the 3.79 MB limit. I also had that problem way back, and it was all because of the file being too big.
If you are using Brawl Costume Manager, try replacing your CSPs and all that stuff via Brawl Box instead. I've noticed that Brawl Costume Manager isn't too reliable, and the only times my game crashed was after adding my mods by using it. Sure, Brawl Box takes way more time, but it's worth it.
Also, keep in mind that you should always compress your images into CMPR format. That decreases filesize even more, and lets you have more space. You can also put CSPs into Photoshop and index color the image (or however you say that) which reduces image quality (almost unoticeable) and also reduces size, if I'm not mistaken.
For BPs and CSS Icons, you can also use Brawl Box. BPs are in a separate folder located in projectm>pf>info>portrite and I always replace compress them into CI8 format, and have never had problems with them. Also, for Result Portraits, located in projectm>pf>menu>common you should also consider using CMPR format. (Please read below for more information)
I've actually been having issues with SSS freezing as well, since I've replaced all the images to indicate which were banned/etc. What are CMPRS and C18, and how would I go about compressing stuff in BrawlBox?
I would recommend using Brawl Box v0.71 or newer (since I use Brawl Box v0.73b) as they are bound to come with an option called "Re-Encode" and that actually allows you to change the format on the images found on common5.pac and the rest (like BPs, Results Portraits, Stage Previews, etc) It's as simple as that actually.
For stages, I also like to use Stage Manager just to replace .pac files containing the actual stage. For previews and icons, I always go into Brawl Box and replace all that stuff manually.
As stated above, you should always go with CMPR, as it compresses the file and reduces its size drastically, while at the same time sacrificing some quality (you won't notice it... well maybe a little but it's nothing too tragic)
On the other side, CI8 (and also CI4 if I'm not mistaken) actually have better image quality, but file sizes are 3 times bigger than those compressed with CMPR. That "better quality" is not worth it, so you should always go with CMPR. Keep in mind that SSS Icons are like CSS CSPs, and maybe there's also a file size limit to them, but unfortunately I don't know it. Trying to keep files small is your best shot at making things work.
I've also had problems wth my SSS freezing but it should be fixed as soon as you replace your stuff manually and do it following what I have explained here. I haven't had any other issues with my current build so I can confirm it works.