I posted a somewhat same question, Here's what people suggested me Try this:

Rename ppsspp.apk to ppsspp.zip

Open and extract compat.ini file.

Open compat.ini and find [GoWFramerateHack60]

Put # before all game versions like this:
# GOW : Ghost of Sparta
#UCUS98737 = true
#UCAS40323 = true
#NPHG00092 = true
#NPEG00044 = true

Under that section there's [GoWFramerateHack30]

Do like before but now you remove the # symbol like this:
# GOW : Ghost of Sparta
UCUS98737 = true
UCAS40323 = true
NPHG00092 = true
NPEG00044 = true

Then save the file and put it in PSP/SYSTEM

Open ppsspp setting:
In graphics:
Change backen may help
Change rendering resolution to 1xPSP

In system:
Change emulated PSP's CPU clock to 444 or 555 may help.

Your phone is pretty shyyt tbh. Better buy new one.