TDP
The wattage a handheld feeds its APU; lower TDP stretches battery life, higher TDP unlocks more frames.
TDP (Thermal Design Power) is the sustained power budget, in watts, that a handheld allows its APU to draw. Most handhelds expose adjustable TDP modes, often ranging from around 5-8W on the low end to 25-40W or more at the top, letting you trade performance for battery life on the fly.
Dropping TDP a few watts often costs surprisingly little frame rate while adding real minutes of battery life, because handheld APUs are usually power-limited rather than thermally maxed out at their low and mid settings. Pushing the top TDP mode usually needs a game plugged in or a big battery to sustain it.
Why it matters when buying
Check how granular a handheld TDP slider is and whether it is set in the vendor app or firmware/BIOS. A device with a wide, easily adjustable TDP range lets you dial in the right performance-versus-battery balance per game instead of being stuck with one profile.