Is the excitement surrounding chipmaker Nvidia fading? As of Monday, shares of the tech giant were down 19% since the start of 2025. Whether that's due to its high valuation, concerns about the economy, tariffs, or the possibility of a slowdown in tech spending on the horizon, investors don't appear as eager to own the stock anymore. What may surprise you is that even over the past 12 months, Nvidia stock has risen by just 20% -- a solid return but not the type investors may have been expecting from the chipmaker, given the growth opportunities in artificial intelligence (AI). Three stocks which have been far better buys than Nvidia over that stretch are Summit Therapeutics (NASDAQ: SMMT), Rocket Lab USA (NASDAQ: RKLB), and AppLovin (NASDAQ: APP). Here's how much these stocks are up, and whether they can still go higher. Summit Therapeutics: +366% The highest-performing stock on this list is from a healthcare company that doesn't have an approved product in its portfolio. But that hasn't stopped Summit Therapeutics from reaching a valuation of more than $14 billion. It may seem ludicrous to value a company so highly, but investors are effectively pricing in the approval of its cancer drug ivonescimab. The hype is due to a recent clinical trial that showed that it performed better than a top-selling cancer treatment, Keytruda, in treating non-small cell lung cancer. Keytruda has generated tens of billions of dollars for Merck, which is one of the largest healthcare companies in the world. If Summit's ivonescimab is even in the same ballpark as Keytruda, then you could make the argument that even at a market cap of $14 billion, it still has much more upside. But U.S. regulators haven't approved the drug. While the trial results were impressive, they were based on a trial in China, where the study participants may not be diverse enough to convince the Food and Drug Administration of its safety and effectiveness. Summit's potential is high, but so too is its risk; ivonescimab is by no means a lock to generate billions of dollars in revenue, but investors are buying the stock as if that's the case. Unless and until the company releases similar results from a more diverse trial, you may be better off taking a wait-and-see approach with this highly-priced stock. Rocket Lab USA: +335% Aerospace company Rocket Lab USA is another stock that has soundly outperformed Nvidia over the past 12 months. The business has been experiencing strong growth and recently capped off a record performance in 2024. Revenue rose by 78% to total $436 million for the year, and the company achieved 16 launches of its Electron orbital launch vehicle (used for small satellites), an increase of 60%.