Looking at this Exagear stuff, it is probably just qemu-based, too - only using the emulation in userland only. That's what those qemu binaries do that do not have the "-system-" in their name. Since the API between kernel and userland is defined and about the same on all platforms (all that is needed is an ABI translation layer), doing such things isn't too hard.|
So if it is a Linux application that you want to run, give qemu-i386 a try. Note that you need to collect the needed libraries for the application in a dedicated directory (like /usr/gnemul/qemu-i386 or similar, qemu-i386 will tell you when run without arguments) - so better prepare the application in a full x86 system and then copy over the needed parts.
I'm quite skeptical over the claimed "5x" improvement, though. This will depend on the workload. If it is kernel bound - e.g. lots of I/O - that might be true. If it is just CPU bound in userspace (algorithmic complexity, say video/audio codecs, encryption, ...), it will be just the same as a full-system qemu.