What makes the Raspberry Pi 4B suitable for a great desktop experience is overclocking. To do it without burning your Pi, you'll need a good cooling solution and a sufficient power supply. Running as root (sudo -i):
cat >> /boot/config.txt << EOF
over_voltage=6
arm_freq=2000
gpu_freq=750
gpu_mem=256
EOF
zram is a kernel module that creates a compressed block device in RAM. Since multiple compression algorithms are available on the default Kernel, you can choose what to prioritize: speed or compression.
apt-get install zram-tools
Change defaults:
vi /etc/default/zramswap
Optionally you can also disable the Raspberry Pi OS default disk swap:
systemctl disable --now dphys-swapfile.service
Most streaming services nowadays require Widevine to work. If you plan on using them:
apt-get install libwidevinecdm0
Hint: The Netflix-1080p browser extension works great when overclocked!