Photographers, in particular, are drawn into the need to upgrade hardware on a regular basis because we make a living from large image files, which, naturally, take a lot of processing power to crunch. But today's resolution increases aren't of the same order as they used to be. The typical increase in sensor resolution is along the lines of 20%, while a couple of years ago, you were more likely to be making leaps of 40%. Of course, there are exceptions. If you're stepping up from a 16-megapixel Nikon D7000 to a 36-megapixel Nikon D800, that's a massive increase, but it's not necessarily the norm for most nature shooters. So, for most of us, these days a new camera doesn't create the need for a new computer, as well.
Software is another driver of hardware purchases, but here, too, new versions of your favorite imaging software definitely will benefit from a more powerful and faster computer, and the software probably will run okay on hardware that isn't right at the cutting edge. Again, there are exceptions for heavy users of HD or 4K video, but if you're primarily a still shooter relying on software like Lightroom and Photoshop, the latest CPU and GPU aren't absolute necessities.
In short, while your current laptop may be a good candidate for upgrades, you may not need to spend the money on a whole new computer. Instead, you can make selective upgrades that are less costly and give you a lot of bang for the buck.
One of the best and most productive upgrades for photographers is the hard drive. Not only does the hard drive store image files, it's also used by image-processing software to mitigate the processing load from the CPU and GPU in the computer. A high-capacity, fast hard drive can make a serious difference in your efficiency. And, if you're working with video files, a fast, high-capacity hard drive is a necessity.
Today, the state of the art in fast drives is solid state (SSD). When they debuted a couple of years ago, SSDs were very expensive, and their relatively low capacity and high prices made the cost per gigabyte too high for most of us. Now, you can get an SSD for your laptop for about $0.90 per GB, which is still more expensive than a fast-spinning hard drive, but it's much more doable.
So, what can you expect from an SSD in terms of performance? There are a couple of ways you can configure your system. You can replace your current hard drive with an SSD of equal or greater capacity, which is an easy swap, or you can use a relatively low-capacity (and, therefore, inexpensive) SSD for a startup disk and keep your current spinning hard disk (or install a much larger one for more versatility) as the data-storage drive. More about how to make this work in a laptop in a moment.
If you use one for your startup disk, the first thing you'll notice is that your laptop will go from powered down to ready to go in a fraction of the time. Also, applications launch very fast. The increase in performance is dramatic. Across the board, disk-intensive tasks like photo processing are extremely fast. SSDs are also incredibly reliable, and they aren't nearly as fragile as spinning media, which is especially nice in a laptop that can get jostled around a lot.
With a laptop, space in the case is at a premium, but if you have an optical drive, there's a simple way to have multiple hard drives; remove the optical unit in favor of a hard drive. How often do you really use optical disks these days anyway? Go online and search for tutorials on how to do the swap. Depending on your computer, it can be easy to do (if you have a MacBook Pro, www.ifixit.com has great step-by-step instructions).