If you have a condenser there is the small filter at the front to clean (inside the door), as well as emptying the water tank, but also they will have another larger filter which you can access and clean out with a hose. It looks like a cartridge.
Check the model you have for actual info but usually you can access via the front of the dryer at the bottom, it unclips and is quite large but makes a huge difference. Should be done every few weeks to reduce energy usage and increase efficiency.
We moved from a vented dryer to condenser when we moved house but condensers struggle more in colder temperatures. Performing the above maintenance though makes a big difference in getting your clothes dry first time in a condenser even in colder months.
Here is an example
Actually, on this subject, anyone have experience with heat pump dryers? Tempted to move from our condenser but heard they struggle in cold conditions, and we'd plan to have it in our garage where the condenser is now
*edit* clean the big filter outside, it's usually filthy!