nginx – fluent-bit high disk I/O

Currently I’m using Fluent Bit v3.1.9 execute nginx log but when it execute the disk I/O servers is increase from around 200 micro seconds to around 1 to 4 milliseconds also I search on Google didn’t found anything can help to solve this issue
this is my fluent-bit config for nginx

[SERVICE]
    Daemon Off
    Flush 1
    Log_Level error
    log_file /var/log/fluent-bit/fluent-bit.log
    parsers_file /etc/fluent-bit/parsers.conf
    plugins_file /etc/fluent-bit/plugins.conf
    HTTP_Server Off
    HTTP_Listen 0.0.0.0
    HTTP_Port 2020
    Health_Check On

[INPUT]
    Name              tail
    Tag               nginx.access
    Path              /usr/local/nginx/logs/access.log
    DB                /var/lib/fluent-bit/app.db
    Path_Key          filename
    Mem_Buf_Limit     50MB
    Refresh_Interval  30