[Koha] Local Cover Images makes Koha very slow

Hello all, We have noticed that by activating Local Cover Images from system preferences affects speed of Koha searching negatively, for example in OPAC interface when searching for a word we discovered (using linux top command) that it loads the page ( opac-image.pl ) many times, May be one for every record in the page, So Koha site become very slow, After deactivating Local Cover Images from (OPACLocalCoverImages) from system preferences Koha site became more faster about twice, I think storing Local Cover Images as a .bin stream in database will be more faster in loading. Is anyone else noticed this problem??? Thanks.