A bit slow with combinations, what should I do to improve speed?

[Salty]

Personally I have tried shadow boxing with weights and found them counter productive to speed. Simply because you have to be tense to hold the weights, which is the complete opposite to what you want to be doing. I instead have attached my elastic rope to an old ankle straps from a surf board, then when i want some resistance when i shadow box i simply strap it to my wrists and shadow box away. That was I get the benefits of resistance without the negative of being tense, I hope that helps mate

[hackey]

I think flexibility is the key to speed. Building muscle is good to a point until it begins to slow your arm.

[AdamGB]

My guess is that you're too tense, lacking 'muscle memory' and probably need to improve your Anaerobic fitness/Explosive Strength

Throw relaxed, you only need to tense a fraction of a second before impact... think of it like whipping a towel. When you do that you whip it out loose , give it a tug just before it hits the target to tense the towel and then *SNAP*

1) Loosen up like I have said

It doesn't require a lot of fitness to potshot singe shots or one twos, combinations on the other hand require you to rapidly fire up various fast twitch (explosive type) muscle fibres

2) This predominantly uses the Anaerobic Energy system so that needs a good level of fitness (it's late so I'm not going to go into it much... a quick google of Anaerobic/plyometric training should do... think sprint style training, sledgehammer/punch out drills etc. I'd go mostly for bag work if your hands/joints can take it because fitness isn't out being in shape... it's about being fit for a specific task, which in this case is punching)

3) Practice! Shadowbox, throw the combos in slow motion. Repetition! You need to have built up the neurological pathways so that you can instinctly think of the combo and throw it... you shouldn't be thinking of each shot... takes up too much time and energy... strong body/mind coordination and a strong Central Nervous system will make it less fatiguing for you to perform because your body doesn't have to fire up as many motor Neurons to produce the muscle contractions.

Bottom line is keep practicing

if What I've typed is a bunch of nonesense to you then forget it, don't dive into this, just have patience and with time you'll see the results.