Load image in runtime from jpg

If i load image to unity from jpg or png files. Image consumes great memory. And after 1.2-1.3 GB memory usage(not total ie usage) web player crashing(The content was stopped because a fatal content error has been detected).

Converting image to DXT1 not effective and as i learn compress in runtime almost not possible(Texture2D.compress too).

A 4096x4096 texture killing ~80-100MB system memory(load from jpg and no alpha also converted to DXT1).

Only way load from AssetBundle? And Why ~1.2 GB memory usage a limit for web application?
Sure if there is no way to load image from jpg with low memory usage, i will look for alternative ways. But why memory usage have a limit or crash? (My total system memory big enough for more and using 64 bit system)

create an asset bundle (-s) with a textures imported by Unity and load them in bundles

this should not use any additional converting/unpacking in runtime and store it packed.