From Longman Dictionary of Contemporary Englishtime/money/energy wastertime/money/energy wastersomeone or something that does not use time etc carefully or well → waster
Examples from the Corpus
time/money/energy waster• FoE pinpointed fridges, light bulbs, washing machines, dishwashers, televisions, and tumble driers as energy wasters.• Although it is easy to dismiss meetings as time wasters, the above indicates why you should take them seriously.• Cons: Writing with pen and paper is perhaps one of the greatest time wasters in the business world.• Good experience and dedication, no time wasters.• Romantic as it may be, a fireplace without glass doors is a real energy waster. 