Can I start by asking why you have 11 repeaters on one network ???
I hope all of the repeaters are associating directly to the root and not other repeaters. You have the throughput for a repeater but if you go repeater to repeater then to root you 1/4 the throughput and so on for everyone you add.
A repeater should be the VERY last choice in any network design and used only when you have no other options. A repeater will mean EVERY packet is transmitted twice on the radio this will halve your throughput and increase the radio contention.
Typically you aim for a a maximum of 20 to 25 clients per AP but as a repeater transmitts everything it recieves back on the radio network you should reduce the number of clients to match this.
Given you have 11 repeaters associating to one root this does not really leave too much room for clients maybe 1 or 2 only.
Now to the problem on the ethernet side.
Try setting both the AP and the switch port to 10Meg Half duplex the symptoms you described can be caused by a speed duplex mis match and 10 half duplex most closely matches the wireless side that is 11m half duplex.
do you see this problem for all clients on the ethernet or only when trying to go from the ethernet side to a wireless client ??
If it is seen on 2 etherent clients communcating then you may have excessive broadcasts etc but a sniffer is you best option to track this down
I hope this helps I know it is not the answer you wanted but I have grave concerns of a network design like this providing you a reilable connection that will server your purpose, better to redsign it now than after it has been fully installed