Extension method for materializing a LINQ method chain to an Array or List without resizing. Mentioned here: https://stefanolsen.com/posts/8-things-to-avoid-to-make-an-episerver-site-go-faster/

CollectionExtensions.cs

// Copyright 2019 Stefan Holm Olsen
//
// Permission to use, copy, modify, and/or distribute this software for an
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
// OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

using System;
using System.Collections.Generic;

public static class CollectionExtensions
{
    /// <summary>
    /// Creates an array from a IEnumerable<T>.
    /// </summary>
    /// <example>
    /// <code>
    /// var pagedList = list.Take(10).ToArray(10);
    /// var viewModels = list.Select(CreateViewModel).ToArray(list.Count);
    /// </code>
    /// </example>
    /// <exception cref="System.ArgumentNullException">source is null.</exception>
    /// <exception cref="System.ArgumentOutOfRangeException">capacity is 0 or less.</exception>
    /// <returns>An array that contains the elements from the input sequence.</returns>
    /// <param name="source">An IEnumerable<T> to create an array from.</param>
    /// <param name="length">The number of items that should be in the array.</param>
    /// <typeparam name="TSource">The type of the elements of source.</typeparam>
    public static TSource[] ToArray<TSource>(
        this IEnumerable<TSource> source,
        int length)
    {
        if (source == null)
        {
            throw new ArgumentNullException(nameof(source));
        }

        if (length <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(length), length, null);
        }

        TSource[] result = new TSource[length];
        int i = 0;

        foreach (TSource source1 in source)
        {
            result[i] = source1;
            
            if (i++ >= length)
            {
                break;
            }
        }

        return result;
    }

    /// <summary>
    /// Creates a List<T> from a IEnumerable<T>.
    /// </summary>
    /// <example>
    /// <code>
    /// var pagedList = list.Take(10).ToList(10);
    /// var viewModels = list.Select(CreateViewModel).ToList(list.Count);
    /// </code>
    /// </example>
    /// <exception cref="System.ArgumentNullException">source is null.</exception>
    /// <exception cref="System.ArgumentOutOfRangeException">capacity is 0 or less.</exception>
    /// <returns>A List<T> that contains the elements from the input sequence.</returns>
    /// <param name="source">An IEnumerable<T> to create a List<T> from.</param>
    /// <param name="length">The number of items that should be in the list.</param>
    /// <typeparam name="TSource">The type of the elements of source.</typeparam>
    public static List<TSource> ToList<TSource>(
        this IEnumerable<TSource> source,
        int capacity)
    {
        if (source == null)
        {
            throw new ArgumentNullException(nameof(source));
        }

        if (capacity <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(capacity), capacity, null);
        }

        List<TSource> result = new List<TSource>(capacity);
        foreach (TSource source1 in source)
        {
            result.Add(source1);
        }

        return result;
    }
}