One of the best practices in .NET Core and C# is to minimize large object allocations. Large object allocations are objects that are greater than 85,000 bytes in size. These objects are allocated on the Large Object Heap (LOH), which is a separate heap from the Small Object Heap (SOH). The LOH is not compacted, which means that it can become fragmented over time, leading to performance issues.

To minimize large object allocations, you can use the following techniques:

• Object Pooling: Object pooling is a technique where you reuse objects instead of creating new ones. This can help reduce the number of large object allocations and improve performance. For example, instead of creating a new StringBuilder object every time you need to concatenate strings, you can use a StringBuilder pool to reuse existing objects.
• Structs: Structs are value types that are allocated on the stack instead of the heap. They are ideal for small objects that are frequently created and destroyed. By using structs instead of classes, you can reduce the number of large object allocations and improve performance.
• Memory-Mapped Files: Memory-mapped files are files that are mapped to memory instead of being loaded into memory. This can help reduce the number of large object allocations and improve performance. For example, instead of loading a large file into memory, you can map it to memory and access it as if it were in memory.

By minimizing large object allocations, you can improve the performance of your .NET Core and C# applications. Large object allocations can lead to memory fragmentation and garbage collection issues, which can cause performance problems. By using object pooling, structs, and memory-mapped files, you can reduce the number of large object allocations and improve the performance of your applications.