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What device are you using? FB runs pretty fast for me on my Mini 4 and iPhone 6. My only issue with it is that its background activity is STILL one of my main battery users no matter what I do.
 
The FB app is simply a horrible piece of crap, a poorly optimized resource drain. Just use Safari and the FB website - on a regular size iPad you can easily use the full site, on a mini or a phone the mobile version is better. Uninstalling the FB app from my iDevices did wonders to their battery life.
 
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