XLR8(Accelerate)

that has the same footprint as an Arduino Uno,
but that runs like an Arduino Uno on steroids

Regular Arduino Uno

By default, the XLR8 behaves just like an Arduino, right down to its timing and 16 MHz clock. However, the XLR8’s clock frequency can be changed, and various functions — like the PWMs — can be implemented using XBs (“acceleration blocks”) inside the FPGA.

For example, the Arduino Uno doesn’t have a floating-point unit, which means it has to clunk along implementing floating-point operations using lots and lots of simple instructions. In turn, this means it executes floating-point operations verrryyy sslllooowwwlllyyy. By comparison, the XLR8 has dedicated floating-point hardware programmed directly into the FPGA’s fabric. Check out this video comparing an Arduino Uno and an XLR8 using floating-point math to generate Mandelbrot fractal images.