与临时表相比，为什么声明表变量非常慢？

My background process is bulk updating/inserting data. I need to store some data in temp table for later use. I have 5 temp tables. If I use temporary table(CREATE TABLE #T) then it will take 2-3 seconds but if I use table variable(DECLARE @T TABLE) then it takes more than 90 seconds. Here is a sample temp table,My background process is bulk updating/insertin