We do a ton of optimization with JFBConnect and each release is tested for speed. Generally, it shouldn't add anywhere near 3 seconds of load time to a page, but if you have things like our debug mode enabled, caching disabled or other settings in certain states, it could cause additional delay. We'd need to see the site and understand what pages are going slow to narrow that down further though.
If you choose to subscribe to JFBConnect again, we'll gladly help narrow down any performance issues you run into. Should you not be able to get things working how you want, we always have a 30-day money back guarantee.
Thanks,
Alex