Anyone having read my Windows Mobile ZX Spectrum emulation bible knows it’s pretty easy to emulate such an inefficient platform even on slow handheld devices (unlike, say, the Commodore Amiga).
Unfortunately, the ZX Spectrum emulator “ZX Gamer 3GS” (AppStore) released some days ago can’t even reach the speed of original ZX Spectrums on the iPhone 3G S, let alone older and slower iPhone / iPod touch models.
What is more, it’s just a complete ripoff of JSSpeccy as is also explained HERE. Which also explains why it’s so slow.
For the time being, stay away from this emulator: it’s both slow and has major Copyright issues. Strange the Apple folks in charge of letting apps into the AppStore haven’t noticed the latter and have approved the title. While they were very fast to remove the, technically, much-much superior C64 Emulator (see THIS for a review) some two days after it hitting AppStore just because it was hackable to gain access to the built-in BASIC interface.
Because of the speed and the questionable legal status, I haven’t even bothered trying to find out whether it’s possible to “hack” any games into it (as was the case with the C64 emulator). It simply isn’t worth bothering.