optim: shallow copy block header in Context

the proto clone introduce significant memory allocations in our
profiling, because the method is called multiple times for each
transaction, and the deep clone seems unnesserary, the header is a plain
struct without pointers inside (unless one that's in time.Time), a shallow value copy seems good enough.

CHANGELOG.md

@@ -91,6 +91,7 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 * (types) [#18963](https://github.com/cosmos/cosmos-sdk/pull/18963) Swap out amino json encoding of `ABCIMessageLogs` for std lib json encoding
 * (x/auth) [#19651](https://github.com/cosmos/cosmos-sdk/pull/19651) Allow empty public keys in `GetSignBytesAdapter`.
 * (x/genutil) [#19735](https://github.com/cosmos/cosmos-sdk/pull/19735) Update genesis api to match new `appmodule.HasGenesis` interface.
+* (server) [#]() Return BlockHeader by shallow copy in server Context.
 
 ### Bug Fixes
 

types/context.go

@@ -6,7 +6,6 @@ import (
 
 	abci "github.com/cometbft/cometbft/abci/types"
 	cmtproto "github.com/cometbft/cometbft/proto/tendermint/types"
-	"github.com/cosmos/gogoproto/proto"
 
 	"cosmossdk.io/core/comet"
 	"cosmossdk.io/core/header"
@@ -91,10 +90,9 @@ func (c Context) StreamingManager() storetypes.StreamingManager { return c.strea
 func (c Context) CometInfo() comet.Info                         { return c.cometInfo }
 func (c Context) HeaderInfo() header.Info                       { return c.headerInfo }
 
-// clone the header before returning
+// BlockHeader returns the header is returned by value.
 func (c Context) BlockHeader() cmtproto.Header {
-	msg := proto.Clone(&c.header).(*cmtproto.Header)
-	return *msg
+	return c.header
 }
 
 // HeaderHash returns a copy of the header hash obtained during abci.RequestBeginBlock