If you want a fast JSON parser for FPC, you may try what mORMot 2 offers.
Some numbers, parsing a JSON array of 8000 objects, for a bit more than 1MB:
- JSON benchmark: 100,267 assertions passed 1.31s
IsValidUtf8() in 16.63ms, 1.1 GB/s
IsValidJson(RawUtf8) in 24.78ms, 790.8 MB/s
IsValidJson(PUtf8Char) in 23.22ms, 843.9 MB/s
JsonArrayCount(P) in 23.26ms, 842.7 MB/s
JsonArrayCount(P,PMax) in 22.74ms, 862 MB/s
JsonObjectPropCount() in 9.28ms, 1.1 GB/s
TDocVariant in 140.43ms, 139.6 MB/s
TDocVariant dvoInternNames in 156.73ms, 125 MB/s
TOrmTableJson GetJsonValues in 24.98ms, 345.1 MB/s
TOrmTableJson expanded in 37.36ms, 524.7 MB/s
TOrmTableJson not expanded in 20.96ms, 411.2 MB/s
fpjson in 810.40ms, 10.6 MB/s
In short, mORMot 2 JSON parser is from 13 times to 50 times faster than fpjson - and I guess JSON tools.