FNAF Models Problem in Modding

I don't know if this is the right place to post this, but if it isn't, you can move it to another section. My question is if someone could help me fix a problem I've been having for a while. I have the FNAF zombie models made by "shipudden," for whom I would be very grateful. The problem is that since they have so many polygons, there comes a point where, with high rounds, the weapons start to disappear from your hands. Supposedly, that's because the "FNAF" zombie models have so many polygons. Could someone help me fix this? I'm working on a project for October, and I'd like to include those zombies so they match the map. I'll include the FNAF zombies below, and if anyone knows a solution, it would be appreciated. I would reduce the polygons, but I don't understand much of Maya, since I speak Spanish and translate almost everything! Thanks for reading.

Models Zombies fnaf:

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FNAF Models Problem