Why is it that skills take so long to level up? 3500 barters, 500 potions crafted and 12-15 hours later I finally got alchemy to level 100. Then enchanting, clicking a dagger, selecting enchantment, confirming and then selecting gem and crafting, takes incredibly long. I know that things like 1 hand fighting etc can be gained over time but things like alchemy for me at least don't get used expect for the 1 time I level to 100 to have 100's of hp potions and never make another one ever again.

Well, there are tricks for Alchemy. For me, I collect as much Giant's Toe & Wheat as possible. XP gained is determined from value of item crafted, and that combo makes a hefty XP Gain. Same rule applies to Smithing, but sadly, not Enchanting. Luckily, though, Iron Daggers & Soul Gems are incredibly easy to come by. Don't power level in one sitting or at the end of a character, that's why it feels so long. Just do it alongside your other skills.

In my sig there is a link (SPOILER HEAVY AND LONG READ) to a topic which provides many leveling techniques aswell as other exploits, but usinging it may ruin your experience if you are playing for the first time

Not to mention if you add the guardian, Mage or thief stone that will add 20% to leveling. Also if youre married that adds an extra 10% on top of that.