The GPU is more than likely 3-4x more powerful. The OpenArena benchmark is a particularly trustworthy test.
GFXBench shows Videocore V to have a 2.5x performance increase over Videocore IV.
https://gfxbench.com/compare.jsp?benchmark=gfx50&did1=35520176&os1=Android&api1=gl&hwtype1=GPU&hwname1=Broadcom+VideoCore+V+HW+%28V3D-520%29&did2=28352303&os2=Android&api2=gl&hwtype2=GPU&hwname2=Broadcom+VideoCore+V+HW+%28V3D-530%29&did4=24975581&os4=Android&api4=gl&hwtype4=GPU&hwname4=Broadcom+VideoCore+IV+HW+%28V3D-435%29
The Pi 4 is Videocore VI.
GFXBench shows Videocore V to have a 2.5x performance increase over Videocore IV.
https://gfxbench.com/compare.jsp?benchmark=gfx50&did1=35520176&os1=Android&api1=gl&hwtype1=GPU&hwname1=Broadcom+VideoCore+V+HW+%28V3D-520%29&did2=28352303&os2=Android&api2=gl&hwtype2=GPU&hwname2=Broadcom+VideoCore+V+HW+%28V3D-530%29&did4=24975581&os4=Android&api4=gl&hwtype4=GPU&hwname4=Broadcom+VideoCore+IV+HW+%28V3D-435%29
The Pi 4 is Videocore VI.
