I have a project about dynamic theming. I have 4 _Layout.cshtml (_Layout1, _Layout2, _Layout3, _Layout4) . When user saves the layout in db, I can get it to ViewStart.cshtml like below

@using Microsoft.EntityFrameworkCore
@using TestDynamicLayout.Data

@inject ApplicationDbContext _context;
@inject IHttpContextAccessor httpContext;
@{
   var host = httpContext.HttpContext.Request.Host.Host;
   subDomain = host.Split('.')[0];
   var layout= await _context.LayoutPages.FirstOrDefaultAsync(x => x.SubDomainName == subDomain);         
   Layout = "~/Views/Shared/" + layout.Name;
 }

But this code will take the subdomain and go to db to get the layout name with every request I think. What is the best practice for performance and traffic heavy sites with theming?

I tried also above code with Session

@using Microsoft.EntityFrameworkCore
@using TestDynamicLayout.Data

@inject ApplicationDbContext _context;
@inject IHttpContextAccessor httpContext;
@{
    var layoutName = httpContext.HttpContext.Session.GetString("Layout");
    if (string.IsNullOrEmpty(layoutName))
    {
        var host = httpContext.HttpContext.Request.Host.Host;
        var subDomain = host.Split('.')[0];

       layoutName  = await _context.LayoutPages.FirstOrDefaultAsync(x => x.SubDomain == subdomain);
       httpContext.HttpContext.Session.SetString("Layout", layoutName);

    }

    Layout = "~/Views/Shared/" + layoutName;
 }

If I use this one how much time I shoul set the session timeout and if admin changes the layout again how can I set it again  to new session for end users?

Or any other suggestion other than _ViewStart?

Thanks.