Performance of internal vs external resistors
If you are using the pin as an input in close proximity to the Arduino there is little reason to use an external pullup.

There are a number of factors to consider.

If the switch is some distance from the chip and/or in a noisy environment it will be more susceptible to interference as the internal pullups are high impedance (20kΩ to 150kΩ depending on model).

If the pin is used as both input &amp; output the pullup can reduce the voltage swing.

In other applications e.g. Raspberry Pi the state of the pin between boot and software initialisation can be significant, but this should not be an issue with Arduino.