delaying schema filtering to improve responsiveness
delaying schema filtering to improve responsiveness

fixes #2657

getredash/redash,getredash/redash,44px/redash,denisov-vlad/redash,moritz9/redash,denisov-vlad/redash,getredash/redash,getredash/redash,denisov-vlad/redash,44px/redash,alexanderlz/redash,moritz9/redash,chriszs/redash,denisov-vlad/redash,chriszs/redash,alexanderlz/redash,alexanderlz/redash,44px/redash,moritz9/redash,moritz9/redash,alexanderlz/redash,denisov-vlad/redash,44px/redash,getredash/redash,chriszs/redash,chriszs/redash