Optimized gdscript prime finder

extends Node

func optimized_sieve_of_eratosthenes(limit: int) -> int:
    if limit < 2:
        return PackedInt32Array().size()

    var primes := PackedInt32Array()
    if limit >= 2:
        primes.append(2)

    var sieve_size:int = (limit / 2) - 1 + (limit % 2)
    var is_prime := PackedByteArray()

    for i:int in range(sieve_size + 1):
        is_prime.append(1)

    for i:int in range(sieve_size + 1):
        if is_prime[i]:
            var p:int = 2 * i + 3
            primes.append(p)
            for multiple:int in range(p * p, limit + 1, 2 * p):
                if multiple % 2 == 1:
                    is_prime[(multiple - 3) / 2] = 0

    return primes.size()

func _ready():
    var start_time = Time.get_ticks_usec()
    var limit:int = 25000
    optimized_sieve_of_eratosthenes(limit)
    var end_time = Time.get_ticks_usec()
    print(end_time-start_time, " microseconds elapsed")