One of the things most people don't realize is just how much energy it takes to get something moving at relativistic speeds. For example, to get a *gram* of mass to move at 87% of the speed of light requires as much energy as the atomic bomb that destroyed Hiroshima. If you wanted to get a kilogram to move that speed, it would take the energy of 1000 such atomic bombs.<quoted text>
This demonstrates that even at non relativistic speeds, there is a tiny increase in mass.
As the speed approaches the speed of light, the increase in mass skyrockets.
Not just the perception of mass, but the ACTUAL mass.
If, on the other hand, you want to get that gram to move at 99.99% of the speed of light, it would take about 70 such bombs. Multiply that by 1000 for each kilogram.