I'm afraid this is due to the new "prim cost" feature implemented for mesh objects: when you select a prim, the viewer queries the server to know what is the prim count equivalent for that prim (1 mesh prim may be equivalent to several "normal" prims, depending on its complexity, its size, the fact it is physical or not, and the fact it is scripted or not).
However, there should be no long freeze (1s seems excessive): maybe you are having network issues... can't tell without a proper log file: please follow this forum
rules and provide the requested data.