First render takes a long time after rebuild

[parsagholipour]

I noticed when I make a change it takes a long time(about 10s) for the page to render for the first time although the build time is fast. After the first time it becomes normal.
I could fix it using the following method:
in my root.tsx I wrapped my whole app in a ClientOnly component.

if (isDev) {
    return <ClientOnly>{() => children}</ClientOnly>;
} else {
    return children;
}

After it the load time is less than 1s.
What could be the reason and Is there a better workaround?
I have to also mention there's no request blocking.

version:
@remix-run/react: 1.17.1
node: 16