Early laptops used to be pretty slow, thick, and heavy. Modern laptops are generally a lot thinner and lighter than previous generations. Some gaming laptops are able to stay pretty close to this low-profile trend while still offering plenty of processing power, other gaming laptops don’t compromise on performance at all, at the cost of increased size and weight.
Over the years, processors have become more and more efficient as the technology required to make them, has been miniaturized further. With each miniaturization improvement, more processing power has been squeezed into the same space, while less power has been required, and less heat generated. This process has allowed for smaller heat dissipation techniques and has reduced the necessity of large batteries.
With advances in computing power, modern laptop design can be based on accurate modelling of the air and heat flow of the system. By simulating designs and tweaking them to be as efficient at cooling as possible, the amount of cooling material can be minimized.
The use of light-weight and strong alloys and plastics in modern laptops is a big part in their lightweight construction. The strength of these lightweight materials and the advent of improved construction techniques has enabled their use as both the exterior of devices and to make up the structure of the laptop chassis.
Battery technology has also seen significant miniaturization and weight reductions. Old school nickel-cadmium batteries were heavy, bulky, and weren’t able to store all that much power. In comparison, modern lithium-ion batteries are a lot smaller, lighter and can hold a lot more power.
While a super thin and light laptop sounds great, they do come with some limitations. Due to the lack of size, it is difficult to cool, which means that laptops can run very hot. The only way to counteract this is to either use less powerful hardware or to increase the bulk and weight of the laptop with increased cooling. Which of these methods is chosen depends on the intended purpose of the device, with most general-purpose laptops leaning towards thin and light and compromising when needed on performance.