This page may contain affiliate links and we may earn a small amount of money from any products bought. Our reviews, however, remain independent and impartial.
Performance Lab Stim holds the honour of being the very first product from Performance Lab that contains caffeine or stimulants. Until now, the range from manufacturer Opti-Nutra has avoided stimulants at all costs. Indeed, they have built a brand around 100% natural non-stim products.
So, what gives? Why design a stim product now? Well, marketing vagaries aside, it looks as if Performance Lab have spotted a gap in the market… namely, the need for safe, balanced but effective stimulation.
Being Performance Lab, they haven’t just thrown a boatload of stimulants into a bottle and left you to struggle. No, they’ve spent a considerable amount of time designing a product that offers, in their own words, ‘cleaner, calmer, healthier stimulation’. Namely clean alertness without the jitters.
Can it really be done? Performance Lab say so, and if this product lives up to the carefully engineered and well thought out products found elsewhere in the Performance Lab range, we’re inclined to believe them. But let’s investigate, shall we?
About Performance Lab Stim
With the above in mind, let’s ask the obvious question: what sort of supplement is Performance Lab Stim designed to be? A cognitive enhancer? An alternative to caffeine pills? Yes, and yes. We wouldn’t be going too far if we described it as a caffeine pill without the crash, thanks to its clever use of ‘smart caffeine’ (more on that shortly).
Could it also be used to aid athletic performance? Caffeine can certainly help with energy, focus, exercise intensity and endurance; it’s nothing if not versatile. Stim may therefore help sport performance in some regard.
We’d be lying, however, if we claimed that the dosage in Performance Lab Stim competes well with the stronger stimulant pre-workouts on the market. It doesn’t. The caffeine included is intentionally low to give you the flexibility to choose your own dose.
Indeed, as this product sits within the CORE Performance Lab range and not the SPORT range, we’re going to say that any boost to athletic performance is a welcome bonus, and not the design of the product.
Instead Performance Lab Stim’s gentle stimulant boost with added ingredients for balance (L-theanine) and recovery (L-tyrosine, B-vitamins) is primarily aimed at helping you multitask, deal with stress, boost your alertness, memory, mood and more whenever you need a helping hand. So, as we said, a clever crash-free caffeine pill.
<<<< Buy Performance Lab Stim direct from the manufacturer >>>
The Formula
Performance Lab Stim boasts a pretty clever formula:
- A gentle boost from caffeine – at 50mg caffeine per capsule, it’s strong enough for a gentle hit, but low enough to allow you to double or even triple your dose if you prefer.
- Promotes anti-anxiety and calmness with 100mg L-theanine per capsule, giving you the best of caffeine without the jitters, anxiety or crash. The caffeine-theanine combo is known as ‘smart caffeine’
- Includes brain helping amino acids such as L-Tyrosine, 250mg, to help sustain focus and mood.
- Plus, B-vitamins to replenish those typically lost with caffeine intake, helping the nervous system deal with stress and more.
Let’s have a closer look at the ingredients and see if Performance Lab Stim really delivers what it promises – to be ‘the most advanced caffeine formula ever developed’.
Ingredients
Natural Caffeine (50mg)
The caffeine in Stim comes from natural sources, specifically coffea robusta seeds. Caffeine has many benefits associated with it; not only can it improve physical performance, it can also improve mental performance, boost mood, and banish fatigue. Caffeine can also help to burn calories by temporarily raising your metabolism and increasing fat oxidation during exercise.
Studies show that caffeine can help you concentrate better, learn more, and can also improve wakefulness. Subjective wellbeing has also been shown to improve after consuming caffeine. If you think of Stim as primarily a cognitive enhancer, then caffeine as an active ingredient is a no-brainer (pun intended!). Helping you to think better, focus more, increasing your attention, and boosting your mood.
Caffeine is also a common ingredient in fat burning supplements due to its ability to increase your metabolic rate and fat oxidation. A 1990 study found that ingesting caffeine led to both increases in metabolism and increased plasma glycol levels – which is evidence of fat burning. The chances are, however, that the dose contained in Performance Lab Stim falls short of the levels needed for effective fat burning, so if this is what you want, you’d be better off choosing a dedicated product, such as Performance Lab SPORT Fat Burner.
Where the 50mg caffeine per capsule is useful, however, is in allowing you to choose your own dosage. Consuming two tablets for 100mg or three for 150mg, for instance, or consuming a single tablet alongside a common caffeine source such as black coffee.
L-Theanine (100mg)
L-theanine is an amino acid that is found in green tea, it is often combined with caffeine because it has a synergistic relationship with it. L-theanine has been found to reduce the side effects of caffeine (jitteriness, nausea, headaches etc). It is also able to reduce anxiety, which caffeine is known to increase.
When combined with caffeine you get all the benefits of caffeine with none of the drawbacks. Providing a clean energy experience.
L-theanine can also increase attention, making it a great supplement ingredient for studying or work, boosting the cognitive benefits of caffeine even further. Enhancing your cognition, allowing you to study better, and relaxing you. The dosage of l-theanine is spot on, with the recommended dosage being between 100 and 200mg.
L-Tyrosine (250mg)
Another ingredient that combines excellently with caffeine. Taking high doses of caffeine can reduce levels of catecholamine which can affect mental performance (even as caffeine improves it). L-tyrosine can help your body to recycle catecholamine and restore your levels to the ideal state. It also helps you to concentrate more, think better, and is an ideal choice to reduce stress during stressful events or help alertness after sleep deprivation. This is the recovery aspect of Performance Lab Stim.
B-Vitamins
It’s obvious that every single ingredient in Performance Lab Stim has been carefully chosen to perform a very specific role. Now it’s the turn of the B-vitamins, Stim’s NutriGenesis® Caffeine Balance B-Complex – B2, 6, 9 and 12. These B vitamins in particular seem to drop with caffeine intake and replenishing them is important.
They act as a counterbalance to caffeine, to help handle the body’s stress, contribute to healthy homocysteine levels (caffeine raises the latter, which can contribute to brain fog and memory issues) and optimise energy. They act as the balance portion of Performance Lab Stim.
Pros of Performance Lab Stim
- Clever combination of ingredients: caffeine and l-theanine, caffeine with L-tyrosine
- Improves focus, mood and attention during work or study
- None of the common drawbacks of consuming caffeine
- Modest amount of caffeine allows you to choose the right dosage for you
- Can be taken with more traditional caffeine sources
- Can be used for improving work/studying
- Can be combined with other Performance Lab supplements (such as their stim-free pre-workout or Performance Lab Energy)
- The NutriGenesis® process ensures the B-vitamins within Stim are more bio-available.
- As always, Performance Lab’s products are 100% vegan, natural and eco-friendly.
Cons
- Caffeine dosage is low when you compare it to traditional caffeine pills – which typically include 100-200mg of caffeine, though you can double or triple your dose.
- You may need two servings or more to feel the effect.

Graphic courtesy of Performance Lab
Safety/Side Effects
Performance Lab Stim should be a safe product. After all, the whole emphasis of the product is ‘ultramodern caffeine for cleaner, calmer, and healthier stimulation.’
L-Theanine is an incredibly safe supplement with ridiculously high dosages still safe when tested on rats. L-Tyrosine can have some side effects, when taken at 150mg/kg (so 9g for a 60kg person) l-tyrosine can cause increased blood pressure and heart rate. However, that is a ridiculously high dosage. You would have to take 36 Stim tablets to get 9g, which would incidentally contain enough caffeine to kill you!
Caffeine is the only ingredient likely to cause any side effects, with high doses being associated with heart palpitations, high blood pressure, nausea, anxiety, jitteriness, upset stomach, and insomnia. But the l-theanine and l-tyrosine in this product would be able to mitigate most of these issues, and you would have to take a lot of Stim tablets to see any issues.
How to Take It?
The beauty of Performance Lab Stim is that you can make up your own dosage – we like to have one Stim in the morning with our coffee, and then another Stim (no coffee) in the afternoon. That’s enough to give us a kick awake in the morning and keep us focused for the rest of the day.
You can play around with how Stim works best for you – just be aware that the daily healthy maximum caffeine dosage per day is around 400mg. Don’t forget to add up all your separate caffeine doses throughout the day. Taking one stim (50mg) with a double espresso (120mg), for instance, will give you a 170mg caffeine hit.
Combining it with coffee is certainly the most economical option to preserve your Stim capsules . There are 30 capsules in a tub.
Who Takes It?
Anyone can take this supplement, there is no specific benefits that are applied to a certain demographic. The people who would see the most benefit from taking Stim would be people who don’t habitually use caffeine, as the results would be superior. Stim could benefit students and professionals alike, anyone wanting a cognitive boost or even a physical one.
Stim could potentially even work for anyone wanting to lower their alternative caffeine intake.
Final Remarks on Performance Lab Stim
Stim by Performance Lab is subtle and well thought out rather than just trying to fry your central nervous system as efficiently as possible. Truth be told, it’s more than just a caffeine pill.
With its modest dose of caffeine, allowing you to adjust your dosage, and its brain protecting amino acids and B-vitamins, it’s a healthier, cleaner choice when you need an energy boost or a cognitive aid.
For that reason, we like this product. Which shouldn’t really surprise us being as it comes from Performance Lab, a range which has proven time and again its commitment to quality, safety and effectiveness.
We think Stim would be great on its own but even better paired with a stim-free nootropic stack such as Performance Lab Mind, or Mind Lab Pro, for all-round total brain health and support. Or with stim-free Performance Lab Energy for a full-on energy boost.
Where to Buy
All Performance Lab products are only available from the official website. You can enjoy a 5 or 10% discount on Performance Lab Stim if you buy in bulk.