Talk -- while the map markers are based on your computer, I suspect that they are queried by the server when they are being used, and I suspect it is the entire array of them that is queried. That would mean that substantial increase in the number of markers would in fact increase the load on transfer and on the server. This is a suspicion, in part based on the fact that the limit numbers have been the usual powers of two. Note that the current limit numbers are twice what they used to be.
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Remembering Tyneetryk
Phaedreas Tears - 15 years old and first(*) of true neutral guilds in Atys.
(*) This statement is contested, but we are certainly the longest lasting.
<clowns | me & you | jokers>