Minimize Current Sensing Loss in LED Driver
You could use a smaller resistor and an op-amp amplifier to boost the signal across R4. If you had a x10 op-amp gain stage, R4 effectively becomes 10x smaller. Don't use any crappy op-amp though - I suspect you'll need something reasonably fast to avoid potential oscillation problems. The op-amp also needs inputs and outputs to work down to the earth rail (as per your circuit. You should be able to steal half a mA from Vcc to power the op-amp. Maybe consider an AD8605 (there will be plenty of others of course).