I'm already working on solving this issue - I have changed the tile loading mechanism to first load the most recently requested added tiles (tiles currently on screen), I am also now discarding old request that were not handled on time - no need to load a tile you scrolled past while dragging the map half a minute ago that is no longer on screen.

Technically - I am now using a circular stack for handling tile loading requests

Results look good so far - definitely feels more responsive while doing fast scrolling and I'm planing some field testing soon (= inter-city bus ride ).

I've got further responsiveness improvements while a lot of tiles are being downloaded (eq. visiting a new area, zooming up in new area, etc.) from the network by setting a lower limit on the number of concurrent automatic tile download threads.

You can try this too - it is already possible to tweak in the current version. Just go to options->network->Network-usage and play with the Max. nr. of threads for tile auto-download option