That’s a bit of a record for a fully running Xfce. Still, browsing can’t be much fun. Have you considered upgrading your single ram chip?
Your lap supports 8GB max (Acer One 14 Z1402 Price (27 Apr 2024) Specification & Reviews । Acer Laptops) and this will make a huge difference. An 8GB DDR3 PC3L-12800 204pin bank is new about 20 $ or around 10$ used. The upgrade should take about 15min: https://www.youtube.com/watch?v=NG9k09tsIHs .