SQLD replica is super slow (due to blocking)?

I've got a test setup of LibSQL SQLD running with a primary and a replica in a docker image. The docker-compose.yml is as follows:

version: "3"
services:
  lsql-1:
    image: ghcr.io/tursodatabase/libsql-server:latest
    platform: linux/amd64
    container_name: lsql-1
    restart: no
    ports:
      - "8051:8051"
    expose:
      - 5001
    volumes:
      - ./data/1:/var/lib/sqld
    environment:
      - SQLD_NODE=primary
      - SQLD_HTTP_AUTH=basic:YWRtaW46YWRtaW4=
      - SQLD_GRPC_LISTEN_ADDR=0.0.0.0:5001
      - SQLD_HTTP_LISTEN_ADDR=0.0.0.0:8051


  lsql-2:
    image: ghcr.io/tursodatabase/libsql-server:latest
    platform: linux/amd64
    container_name: lsql-2
    restart: no
    ports:
      - "8052:8052"
    expose:
      - 5002
    volumes:
      - ./data/2:/var/lib/sqld
    environment:
      - SQLD_NODE=replica
      - SQLD_HTTP_AUTH=basic:YWRtaW46YWRtaW4=
      - SQLD_PRIMARY_URL=http://lsql-1:5001/
      - SQLD_GRPC_LISTEN_ADDR=0.0.0.0:5002
      - SQLD_HTTP_LISTEN_ADDR=0.0.0.0:8052
networks:
  lsql:
    driver: bridge

This is running on a Minisforum EM780 with 32 GB of RAM. Specs can be found here: https://store.minisforum.com/products/minisforum-em680

Using a test script that performs a number of basic read/write operations (visible here: https://github.com/hiraeth-php/turso/blob/master/test/index.php) I get wildly disparate execution times running it against the primary vs. the replica. The latter being an order of magnitude (over 1 second), slower. Here's the results from time runs:

Running on the Primary
________________________________________________________
Executed in   75.91 millis    fish           external
   usr time   26.64 millis    1.46 millis   25.17 millis
   sys time   15.02 millis    0.63 millis   14.38 millis

Running on the Replica
________________________________________________________
Executed in    1.16 secs      fish           external
   usr time   39.42 millis  833.00 micros   38.59 millis
   sys time   10.52 millis    0.00 micros   10.52 millis

You can see the replica is over 1 second, however its usr and sys times are not wildly different, which suggests the replica is doing a lot of blocking waiting on and/or syncing with the primary. None of this should really be network latency, as both instances are just two docker containers on the local system talking to one another.

Reproduce the reported timings from docker-compose.yml using the test script in test/index.php, comparing the primary and replica containers. Start by checking replica synchronization and blocking behavior, then document the cause and a verified way to eliminate or explain the over-one-second delay.