Not really, but you give very little detail on what exactly you are doing so this answer is merely a guess. You essentially have 3 options in PD available depending on what hardware and video formats you have.
1) use CL SVRT, low load on both the CPU and GPU as all unedited source footage is simply passed through to the end produced file when input and output formats are matched.
2) use GPU for encoding, or hardware acceleration as its called. Typically creates a high load on GPU as it's doing the rendering and a low cpu load as it's primarly just doing I/O
3) use CPU for encoding. Typically creates a high load on cpu as its doing the rendering and I/O and a low GPU load as it's doing very little
Is GPU always faster, not necessarily, a high end multi core cpu can outperform a mid level GPU so it depends what's under the hood.
Is CPU always faster, not necessarily, a high end GPU can easily outperform even a high end cpu so it depends what's under the hood.
During CPU encoding, are the CPU's always pegged at 100. Sometimes no, depends on what's limiting in your system. At times I/O either windows pagefile or PD can limit effective use of the cpu to render.
Do SVRT, GPU and CPU encoding produce the same quailty. Not necessary. depends on hardware and produced formats.
Jeff