I found out that in act 4 the bounty quests are much faster than in any other act. There are few bounties you do not want to do if you want to run it as fast as possible.
Those are
Killing diablo: This one is probably the worst of all just leave game and create again.
Killing izual: Izual is easy, but you have to run though whole silver spire 1 which takes some time.
Good thing is you can finish all bounties and than invite all your friends into game. After all join just speak to tyrael and all your friends will get the horadric cache aswell.
Getting horadric cache requires you to finish all five challanges in any act you pick. In act IV here are some challanges i met in my play.
First ones:
Killing Rakanoth: Quite easy one just run to him (takes about 30s if you ignore all mobs) and kill him. His dmg isn't high so he should not give any problems.
Cursed dias: This is the best challange you can get. All you have to do is run north after teleport active shrine and kill few waves (You get resplendant chest if you finish all 5)
Killing some random boss + 100 mobs: This one is fine aswell. Killing 100 enemy is not that time consuming because there are many crawlers and 100 adds up quickly. The random miniboss is usualy even weaker than rare mob so it shoud be fine.
Second ones:
Killing some random boss + 100 mobs: Same like the first one.
Third ones:
Killing sledge: This one is better alternative. You must get to rift lvl 2 (You can ignore all mobs and just run through) On level 2 there is sledge who is very easy to kill.
Killing everything on rift 2: This one is a bit more annoying as you must kill all mobs in rift 2 (You can ignore mobs in rift 1).
Fourth ones:
Kill random boss + 100 mobs: Harder than the one in gardens but still doable in solid time. Just watch out for some nasty rolled elites.
Kill izual: The one i spoke about earlier it is not that bad I dont remake game when i have killing izual but it takes a bit more time than random boss if you are not lucky with entrance.
Fifth ones:
Cursed chapel: This is the best you can get here. It is cursed chest with lot of easy trash so it is quite easy to even get 2 resplendant chests if you have solid aoe dmg.
Kill boss + 100 mobs. Same like the fourth one.
Kill diablo: Terrible one takes lot of time i allways remake game if i get kill diablo bounty.