Instead of removing whole modpacks, get a bukkit plugin called Tekkit Customizer. It will allow you remove specific items from the game without remove whole modpacks. For griefing I would reccomend removing nukes, red morning stars, destruction catalysts, nova catalysts, and nova catalysms. For lagging remove dimensional anchors and automatic crafting tables mk2. Energy condensers/collecters can give players infinitely many items if that is a problem. Nuclear reactors can have destructive meltdowns if that worries you. Forcefields can be a cheap protection system if you plan to allow sharing of houses. Also, some choose to ban swiftwolf's rending gale as it allows players to fly. If your server is going slow, remove the computercraft modpack. It can cause lag problems on low end servers. Railcraft can also cause lag problems on low end servers.