Why are the recommendations locked

After further investigation, I found that the same type of up/down performance was happening when I as running some code I had written. I found out that my computer was throttling back resources due to heat. I have, since, got a laptop cooling fan and can now play FF14 on max settings without overheating (and thus losing performance)

My understanding is that when a buyer standing at market board in a city-state purchases items from a retainer that is stationed in a different city-state (as noted by the nation icon on the market listing), the purchase price will be slightly higher to account for an additional "delivery fee." For example, if a buyer in Ul'dah purchases an item from a retainer stationed in Gridania, an additional fee will be added to the purchase price of the item.

As far as I know, the amount of tax incurred by the seller will be the same regardless of which nation the item is purchased from. I don't recall offhand whether the "delivery fee" is simply removed from the economy, or if it goes to the seller. (If I had to guess, I'd choose the former.)