Okay, a couple of things:
1. Instead of every tick, you should use a framerate independent condition like Every X Milliseconds. This will ensure that your rain will fall at the same rate on all computers.
2. Physics can be demanding on the CPU, so you should only use it when you absolutely need it. You should have some events to fade out raindrops and destroy them over time (in case they aren't reaching the water) and also to destroy them if they are beyond the bottom of the layout (some of them are escaping the left edge of the level). By reducing the number of physics collisions you will reduce the load on the CPU.
3. You can get a more efficient spread of rain using a loop like so:
This gives a nice, rainy feel and you don't have to spam rain every tick.
4. There is a picking issue when you spawn from an object based solely on a "every tick" or "every x milliseconds" condition. The SOL doesn't know which Rainmaker you mean, so it's picking the first one in the layout, which happens to be the small one off the screen in the left corner. That one is spawning things normally, while the one in the level is making a weird stream and acting funny. If you specify that you want all rainmakers to spawn things like that then it will work fine, but you need to pick the rainmakers somehow. I added a "For each rainmaker" loop to do so, but you could pick them another way if you like. Anyway, it works fine this way, just change your event to look like that.