I had some trouble installing tekkit lite at first so I tried tekkit classic. It's a bit much for the pi I think, it kept crashing. I have stress tested, setting off 2 separate nukes, oe with 1 warhead, another with three. No lag whatsoever. Quarries don't lag the server, nor does pumping ( I have a geothermal facility now!) It's great.
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Visit my website with the original instructions on it for both vanilla and Tekkit Lite Servers: www.picraftbukkit.webs.com