In Windows, 32-bit processes are limited to 2gb, and Java is going to use part of this for its own overhead, so you're really stuck in terms of how much RAM you can allocate for Minecraft. There is an option though, called 4gb Tuning, which I really don't recommend, that can allow 3gb per process. It could break a lot of stuff, so use at your own risk. And make sure you know how to turn it off again beforehand.
Honestly I would just strip mods out of the packs. That's what I've always done. You're probably not going to use a lot of them anyway. Despite having the hardware, I was a 32-bit holdout for a long time for technical reasons, and I can tell you that 64-bit does make a noticeable difference in Minecraft's performance.
Honestly I would just strip mods out of the packs. That's what I've always done. You're probably not going to use a lot of them anyway. Despite having the hardware, I was a 32-bit holdout for a long time for technical reasons, and I can tell you that 64-bit does make a noticeable difference in Minecraft's performance.