I became concerned when it started doing this on a different Pixelmon server (Server 2) whenever I'm in a battle, regardless of my location. I was battling fine all day when I started seeing the same 0fps drops as experienced on the previous server. This started 3 days ago and has not fixed itself since. It does this in single player and all servers now.
I'm now very concerned because today I experienced the same drops in a location far from spawn in Server 2. I was visiting a friend's house and was hit with crippling 0fps drops, to the point where I had to shut down Minecraft to make it stop. It was a simple build and area with no apricorns - nothing in particular that would cause lag as extreme as this.
Do any of you have a solution or theory as to what might be causing this? I swear I've tried everything from updating Forge, updating my Java, adjusting render distance, using Optifne, taking all my mods out except for Pixelmon, etc. I even have 2GB of RAM allocated to Minecraft. I am using a 2014 MacBook Pro (please do not say "well there's your problem!") with 8GB of RAM and running OSX Mavericks. I'm wary of downloading Yosemite because of the horrible reviews it has gotten.
TL;DR - I'm getting 0fps drops in certain areas of different Pixelmon servers, and it's happening more and more frequently. Any help is greatly appreciated!