you know, there might be some ways to get around the limitation of having not enough cpu and ram, one of which is to make your song relatively simple. orrr you could work on one part of the sound, tweak it with the effects you want to put, save it as an audio file, then put that into your project to make it less laggier.
that being said, sorry but not really a fan of what i'm hearing here. that shitty finale you said was actually fine. now its at the beginning where everything gets so muddy and bitcrushed, almost as if you used something like effector or something on all the sounds. now if that were to be the case, then i don't understand your intentions in applying such an effect. (but i hope its just technical issues) since i dont have my earphones with me its hard to touch on the mixing part after the beginning.
as for the composition itself, i dont really vibe with the melody itself (although it does accomplish the vibe it was supposed to give like a %war victory%) and it gets pretty boring once i realize it repeats for half the song but with different instrumentation, maybe you should've had a different melody played at the beginning, and have the main one play as the drop. the other half of the song is the hard bass parts (that i liked), which could've been better had they been present at the beginning, giving a nice buildup to the song. drum-wise its just- eh. just saying you should add a hi-hat or some percussion to finish your drum sets, otherwise it just feels hella empty
p.s. don't know why you take this as dnb. you do have the bass part going on, but i dont see you having the fast drums or its other half that completes the genre. but hey that matters little to me anyway, its the song that counts