Because I want to use my Android tabled where is no internet connection I started to exporting openstreet map for target area. There is problem with exporting to PRC (It makes excetipons and similar strange problems). So I making BMP files and then I use OziMapConverted that does the job (BMP to PRC) very well and it is fast. But problem is with QV. I export into 13000x13000px tiles because of PRC size restrictions.
The problem is that first map (BMP) is generated very fast, second is slow and next one is very slow. Usually I can make 4 or 5 maps in first hour, next 2-3 hours I get 2 or 3 maps and then 1 map per hour and it is getting slower and slower. The computer hard drive during this operation does not stops. There is a lot of RAM but page error counter increases for thousands each second. It seems there is something wrong in export procedure. I'm not sure but it seems it gets more and more memory during the time. If I stop export, close QV, reopen QV, create map tiles again, remove already exported tiles and continue, than it is again very fast with first tile and getting slow. If I just stop export do not close QV, and start another export than it is as slow as previous tile in stopped export. The QV must be restarted to have first tile fast.
I'm not sure if it is only with onlime maps. I plan to export some topo vector map also. Than I will see if it is issue only for online maps or for any maps.
For example I'm exporting Iceland OSM map in 19% zoom and I have been doing for 2 weeks and I have 2/3 
