How does a carry lookahead adder improve performance over ripple carry adder?

Ripple carry adder has delay proportional to bit width (n) as carry propagates through each stage. Carry Lookahead Adder (CLA) uses generate (G = AB) and propagate (P = A XOR B) signals to compute all carries in parallel. Carry equations: C1 = G0 + P0*C0, C2 = G1 + P1*G0 + P1*P0*C0, etc. This reduces delay to O(log n) at the cost of more complex logic. Practical implementations use hierarchical CLA with 4-bit blocks, achieving good balance between speed and complexity.