Speeding up the game

In a recent playtest of my Chemistry game, it was discovered that the game slows to a crawl as a result of three factors:

Clarity of Goal Cards: It's my fault that the goal cards don't look exactly like what it would look like when the hexes are put together. I can fix that on my own.

Set Collection Problem: As a player is trying to put together their molecule with atom hexes, their ability to get the atom hexes they need can keep them stuck for a long time in one spot. Although the proportions of atoms are correct according to statistical demand, they often get stuck waiting for the right atom, since when another player finds the atom they need, they just stick it on their own molecule.

Goal Size: As players are putting together big molecules, they get bashed down too often because other players see that they're about to score lots of points, and they feel that it's not very fun. Should I get rid of big goals and make it about little sets?

Drawing: My current drawing system is "On your turn, you may draw three atom hexes, three action cards, or a combination of the two not exceeding 3 total." However, what ends up happening is that players who are stuck end up drawing lots of action cards to mess with other players since they feel there's little hope in finishing their molecule.

Finally, the overall time to play is too long for a game like this. If it was Axis and Allies, we could handle it, but the game doesn't get players as invested, so they don't grow attached to it for that long (though they all said that they enjoyed a lot of aspects of it; just the length was a bit much.)

Ideas on how to fix any of that?