No, not 800k. That might be the compressed file size for a jpg, but in memory, they have 1024*1024*4 bytes each, i.e. around 4mb per texture. So 5 textures of that size means 20mb of data on the gpu plus the (maybe compressed) size that they need in main memory to backup the data in case of a context switch. 1024*1024 is a bit too much for a mobile device IMHO.