Short answer is yes, it can be improved.
Long answer, it is not so easy, as on low zoom level and high res game needs to render way more tiles, which significantly slows it down. Whole map rendering process was rewritten to make it smoother and now it does batch sprite processing, so GPU is getting some load. Unfortunately, due to the old nature of DX9, it is not possible to offload rendering to GPU and lots of preprocessing needs to be done on CPU. IOW, it will never fill the same on various zoom levels. But some improvement could be done.
As for drag scrolling, technically it is possible, but it comes into conflict with existing mouse map click routines.