High latency on Amazon S3's getObject from a Lambda function

I'm using a lambda function to serve png files stored in an Amazon S3 bucket. I need those to be pulled relatively quickly (<300ms) for user experience reasons.

The issue I have is getting a single small (<100kb) object from my Amazon S3 bucket takes 300ms+ every single time

My code is quite basic:

def loadS3Object(key):
    bucket = 'bucketname' 
    s3=boto3.client('s3')
    http=urllib3.PoolManager()
    try:
        myObject = s3.get_object(Bucket=bucket, Key=key)
    except ClientError as e:
        return False

1. Is there a way to reduce latency?
2. Or should I use something else than S3 for such a latency-sensitive need?

Thanks a lot!