What explains the situation when the increase in slice size is not proportional to doubling, and why does this happen?

In Go, slices have an underlying array that increases in size when elements are added. However, the growth of the slice's capacity is not always proportional to doubling because the expansion mechanism is optimized for a balance between performance and memory usage.

When the slice is small, the capacity usually doubles during expansion. But once a certain size is reached, the growth becomes more conservative (for example, increasing by 25%) to avoid excessive memory allocation.

This is done to:

• Reduce memory fragmentation
• Optimize resource usage
• Prevent sharp increases in memory consumption with large slices

Thus, the capacity increase of a slice is adaptive and depends on its current size, which explains why the growth is not always strictly proportional to doubling.