Ever since i got dragonborn dlc for xbox theres been a 3 second switching delay when changing from spells to two handed or one handed its annoying me anyway this can be fixed

This has been annoying me too. Sometimes by the time I draw my sword, an enemy has already killed me. I'm not sure when this started, but you may be correct that it has to do with the Dragonborn DLC being installed. I don't know of any solution even though my game is otherwise running smoothly.

I've always had this... since I first got skyrim.

The weapon switching delay has, indeed, slowed considerably with the addition of this dlc.
It never existed in my game until installing Dragonborn.

Though not game-breaking it can be quite annoying.

Switching weapons in combat has always been slow, I stopped doing it because of it.

Does this issue exist with all weapons, or just some of them? Do the Hotkeys help or not?

Now that you mention it, I think there may be certain weapons that are worse than other (in terms of switching/draw time). I would need to confirm this for sure, but I think maybe the heavier (and stronger) weapons like ebony might take longer than lighter (and weaker) weapons like steel. While the two available hotkeys are helpful they don't seem to make any difference in terms of draw speed or switching time when compared to using the favorites menu. Although this seems unlikely, I may have noticed a reduction in the time to switch and draw weapons due to the fact I recently followed the steps on the following page to clear my system cache (because of crashing/freezing issues): http://www.gamesas.com/topic/1426775-starting-dragonborn/ (third post down, labeled "Clearing the System Cache."

I am wondering if the reason why weapon swapping was slowed down, was because the game is now having to load in all the data for the new weapon you are swapping to, when it wasn't doing this previously. Note that DLC and patches require extra memory to be used up (from what I understand on the Xbox, patches always need to reside in memory). Now, remember the problems of large savegame sizes, i.e. they eat up memory, and when savegames reach a certain size, then the game more frequently has to swap data in and out of memory from the HDD in order to run the game, resulting in choppy framerates. So, as more DLC and patches are released, more memory is eaten up because of the overhead of keeping more stuff in memory. So, to prevent the game having poor framerates, they have to reduce the amount of memory used up by 'something'. This 'something' is actually a change to the weapon system, such that only your currently active weapon is held in memory during play. When you swap weapons, the game must load the data in from the HDD, and it cannot display anything until the HDD has transfered its data into memory (because drawing half loaded graphics would be a mess!). Hence, the game literally has to wait for the HDD to completely finish transfering all data (i.e. the textures and geometry of the new weapon you are swapping to), before it can display it on screen.

Note that this is just an idea, based on the game needing to fit more data in memory due to patches and DLC, but the amount of memory available on your system is constant.

I started having this problem with this DLC. I use one-handed weapons and changing from a spell to the sword is really slow. I have not gotten killed yet because of it, but it is really annoying.