The answer to 'why is my faucet slow draining' is that a slow-draining faucet is often caused by a clogged drain or buildup of debris in the faucet aerator. This can happen over time as hair, soap scum, and mineral deposits accumulate in the drain or aerator. A slow drain can also be caused by a problem with the sink's p-trap, which is the curved pipe underneath the sink.
If the faucet is slow to drain, you'll first want to check the aerator at the end of the faucet. Unscrew the aerator and remove any debris or buildup. You can also try using a small wire brush or toothpick to clean out the aerator. If that doesn't fix the issue, you may need to disassemble the faucet to clean out the internal components or replace the cartridge. For a clogged drain or p-trap, you can try using a plunger or a drain snake to clear the blockage. However, if the slow draining persists or you're not comfortable doing the repairs yourself, it's best to call a professional plumber to diagnose and fix the problem.