Alright so a few things to consider but first off yes it will be a significant increase especially if its all the space you need. Solid state drives have really small amount of space and the more gigs you get the faster the price rises.
If the one you are looking at wont be enough space for what youll be working on (ie lets say you buy a 100gb ssd but need 200gb to install) id be very hazardous about changing drives heres the deal. If you try to remidy the problem of space by installing a second drive and you install it to that drive you now are no longer referencing the ssd for most of the computations. Youre new bottle neck becomes the transfer speed between your secondary drive and the motherboard.
Ssd's are actually slower when put into raid systems. If you dont know what raid is dont worry you dont have one if you do then I dont need to explain it look it up.
Bottleneck on your motherboard buss is now days a rare problem but still could exist. If youre unsure what that means think of it this way comparing to roads. Lets say your ssd has 5 lains of auto bon freeway, youre cord can support up to 3 of those lains during transfer and youre motherboard can only read in one redneck rusty car at a time. While the ssd has the answer you are limited to 1 rusty car at a time. Check the manual if your concerned here.
Ssd's still have doa and life expectancy issues like everything else look into the drive make sure its been around for a while.
Performance upgrade is a slightly ambiguitous term, without your comp spec I cant say anything definitive about if you should replace the hd or if maybe ram or processor or graphics card are actually the problem here. I know for most people its usually RAM》hd》graphics card》bad computer management》cpu&motherboard.
Since cpu has specific socket types I just put them together for now.
Feel free to ask questions or post your specs.
Keep in mind new hd means you should have youre bases covered for operating system.