How to Optimize String Concatenation in Go

Performance

2026-04-17T12:05:42+00:00

Use strings.Builder instead of the + operator to efficiently concatenate strings in Go without excessive memory allocation.

Replace the + operator with strings.Builder to avoid creating intermediate string allocations during concatenation.

import "strings"

var sb strings.Builder
sb.WriteString("part1")
sb.WriteString("part2")
sb.WriteString("part3")
result := sb.String()

For loops, pre-allocate capacity if the total length is known:

var sb strings.Builder
sb.Grow(totalLength)
for _, part := range parts {
    sb.WriteString(part)
}
result := sb.String()