Different Data speeds with different roms

Why is this occuring? I'm using speed test, and the three roms i've tried kyobi has the strongest data speeds. I'd rather use poprocks rom from mega, but, the data speeds were about 20mb less.... Is this a modem or kernal issue? i've flashed the same kernal on all three.. I know poprocks was 5.0.1 vs 5.1.1 too. But even for Paul Pizz rom, data was slower... according to speedtest.net

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