I used to get tons of water in the lazertte after heavy rains until I figured out what I believe was the culprit. The two drain holes underneath the cockpit access door on opposite sides would get clogged from debris. Any particles on the boat (dry leaves, spiderwebs, bugs, etc.) would make its way into the channels under the cockpit access door every time I rinsed off the boat or it rained. Now I make it a habit to always wipe down the entire channel, door, and drains every time the boat gets wet.
Since doing so, I have not had water in the lazertte for several years now.
As far as the cockpit drains draining slowly, I have to regularly remove the caps with a spanner wrench to clean out any debris which get in there as well. This usually speeds the drain. In addition, the hoses for which these drains are attached may also have debris lodged in them as well.