linked servers are slow for updates; it's usually because the far table (which might be huge) gets copied over into a local temp table, then the data is merged for the update, adn then the commands are sent back to the far server.
both methods, whether EXECUTE AT, or a direct update, are going to do the same thing...the only difference whoudl be where teh data gets hashed togetehr in the temp tables...AT the linked serve,r or locally by copying the data from the linked server.
how many rows are being actually updated?
--help us help you! If you post a question, make sure you include a CREATE TABLE... statement and INSERT INTO... statement into that table to give the volunteers here representative data. with your description of the problem, we can provide a tested, verifiable solution to your question! asking the question the right way gets you a tested answer the fastest way possible!