szymekpl

-1 - world_nether 0 - overworld 1 - the end if I'm not mistaken

If you want some good 'INVSEE' plugin working with tekkit, use OpenInv plugin for Bukkit-like servers (e.g. MCPC+) http://dev.bukkit.org/server-mods/openinv/

On clean Forge/Vanilla server just use /time set day or /time set 0. Normally you don't have to type world, it's defaulting to actual active world. If you've got problems, use NEI cheat mode or install any 'Essentials-like' plugin ;)

First thing i thought after reading this was: Tequilla (Tekkit + VaniLLa)

That is BuildCraft bug and will be fixed as soon as some other mods will be released for MC 1.5.2 Ref: http://forums.technicpack.net/threads/lags-caused-of-high-ethernet-usage.43958/

I can confirm this issue as well. Here's my log: http://pastebin.com/ACHszn8X