Even if they run only a window manager 2gb if RAM is just not enough for web nowadays.
Recently resurrected a 10-ish year old Lenovo Chromebook-like with an atom CPU and 4gb RAM, running nothing but qtile as a DE and it’s struggling with more than 5 tabs open.
Upgrade the RAM to at least 4gb, preferably 8 and the HDD to SSD.
Also, don’t bother with “lightweight” browsers, in my experience Firefox simply runs much faster.