Reading many small files from S3 very slow

Loading many small files (>200000, 4kbyte) from a S3 Bucket into HDFS via Hive or Pig on AWS EMR is extremely slow. It seems that only one mapper is used to get the data, though I cannot exactly figure out where the bottleneck is.

Pig Code Sample

data = load 's3://data-bucket/'  USING PigStorage(',') AS (line:chararray)

Hive Code Sample

CREATE EXTERNAL TABLE data (value STRING) LOCATION  's3://data-bucket/';

Are there any known settings that speed up the process or increase the number of mappers used to fetch the data?

I tried the following without any noticeable effects:

• Increase #Task Nodes
• set hive.optimize.s3.query=true
• manually set #mappers
• Increase instance type from medium up to xlarge

I know that s3distcp would speed up the process, but I could only get better performance by doing a lot of tweaking including setting #workerThreads and would prefer changing parameters directly in my PIG/Hive scripts.