对于在AWS EFS上运行的SQLite只读数据库，可使用以下两种方法来提高并发读取性能：

1. 配置并发访问：可以使用Python中的sqlite3模块配置数据库连接。在事务完成时，需要关闭SQLite连接。这可以确保为每个读写请求提供单独的连接。

import sqlite3
import time

# Connect to database
conn = sqlite3.connect('/efs/data/example.db', check_same_thread=False)

def read():
  # Open cursor and perform read
  cursor = conn.cursor()
  cursor.execute("SELECT * FROM example_table")
  rows = cursor.fetchall()
  cursor.close()
  time.sleep(1)

# Run multiple concurrent reads
for i in range(10):
  read()

# Close database connection
conn.close()

2. 使用缓存：使用Redis或Memcached等缓存工具缓存读取请求结果。这可以减少重复访问SQLite的需要。并且，这样做可以缓解并发读取性能问题。

import sqlite3
import redis
import time

# Connect to Redis cache
cache = redis.Redis(host='redis.example.com', port=6379, db=0)

# Connect to SQLite database
conn = sqlite3.connect('/efs/data/example.db', check_same_thread=False)

def read():
  # Check cache for result
  result = cache.get('example_table')
  if not result:
    # Perform read
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM example_table")
    result = cursor.fetchall()
    cursor.close()
    # Update cache with result
    cache.set('example_table', result, ex=60)
    time.sleep(1)
  else:
    # Use cached result
    time.sleep(0.1)

# Run multiple concurrent reads
for i in range(10):
  read()

# Close database connection
conn.close()