interface designer is extremely SLOW to edit at times.... to the point of being useless 1- 5 sec lag

[Mike_Shaw1]

I am confused. I do not have very many records but some tables have about 150-250 fields per record.  When I use the interface designer is it the SLOWEST thing to edit, to the point of being useless. Why would this be as I only have like 200 records in most cases? It  also seem to happen in the evening a lot but I do not have any other extra  computer processes running compared to any other times. I'm getting lags of half a sec on selecting fields normally, I have to literally "Select" say "one one thousand"  then move the field.... but then at evening times and such and a few others I'm getting like a  1-3 second lag time on field selection response and occasionally up to 5! My latency is like 27-33 fyi.