diff --git a/pkg/sessionctx/vardef/tidb_vars.go b/pkg/sessionctx/vardef/tidb_vars.go
index 1ab8cc5e66476..26ccb6f843ba1 100644
--- a/pkg/sessionctx/vardef/tidb_vars.go
+++ b/pkg/sessionctx/vardef/tidb_vars.go
@@ -540,6 +540,8 @@ const (
 	TiDBMaxPagingSize = "tidb_max_paging_size"
 
 	// TiDBPagingSizeBytes is the byte budget per coprocessor page.
+	// A non-zero value takes effect only when Resource Control is enabled and the active Resource Group
+	// is non-burstable (has limited burst).
 	// 0 means disabled (no byte-budget paging).
 	TiDBPagingSizeBytes = "tidb_paging_size_bytes"
 
@@ -1517,7 +1519,13 @@ const (
 	DefInitChunkSize                        = 32
 	DefMinPagingSize                        = int(paging.MinPagingSize)
 	DefMaxPagingSize                        = int(paging.MinAllowedMaxPagingSize)
-	DefPagingSizeBytes                      = 0
+	// DefPagingSizeBytes defaults byte-budget paging to 4 MiB. It takes effect only when Resource Control
+	// is enabled and the active Resource Group is non-burstable (has limited burst).
+	// Regression tests across cap-bound and under-cap TPC-C, FullScan, and Join workloads found no
+	// material performance regression. Among the tested 1, 2, 4, 8, and 16 MiB candidates, 4 MiB
+	// provided the best overall balance of throughput, tail latency, RU stability, RPC overhead, CPU,
+	// and RU efficiency.
+	DefPagingSizeBytes                      = 4 * 1024 * 1024
 	DefMaxChunkSize                         = 1024
 	DefDMLBatchSize                         = 0
 	DefMaxPreparedStmtCount                 = -1
diff --git a/pkg/sessionctx/variable/setvar_affect.go b/pkg/sessionctx/variable/setvar_affect.go
index f485f62204a7b..befd35dd9ff27 100644
--- a/pkg/sessionctx/variable/setvar_affect.go
+++ b/pkg/sessionctx/variable/setvar_affect.go
@@ -92,7 +92,6 @@ var isHintUpdatableVerified = map[string]struct{}{
 	"tidb_max_chunk_size":                             {},
 	"tidb_min_paging_size":                            {},
 	"tidb_max_paging_size":                            {},
-	"tidb_paging_size_bytes":                          {},
 	"tidb_enable_cascades_planner":                    {},
 	"tidb_merge_join_concurrency":                     {},
 	"tidb_index_merge_intersection_concurrency":       {},
diff --git a/pkg/sessionctx/variable/sysvar.go b/pkg/sessionctx/variable/sysvar.go
index 9df474aefe435..759a6f893f21d 100644
--- a/pkg/sessionctx/variable/sysvar.go
+++ b/pkg/sessionctx/variable/sysvar.go
@@ -3070,7 +3070,7 @@ var defaultSysVars = []*SysVar{
 		s.MaxPagingSize = tidbOptPositiveInt32(val, vardef.DefMaxPagingSize)
 		return nil
 	}},
-	{Scope: vardef.ScopeGlobal | vardef.ScopeSession, Name: vardef.TiDBPagingSizeBytes, Value: strconv.Itoa(vardef.DefPagingSizeBytes), Type: vardef.TypeUnsigned, MinValue: 0, MaxValue: math.MaxInt64, SetSession: func(s *SessionVars, val string) error {
+	{Scope: vardef.ScopeGlobal | vardef.ScopeSession, Name: vardef.TiDBPagingSizeBytes, Value: strconv.Itoa(vardef.DefPagingSizeBytes), Type: vardef.TypeUnsigned, MinValue: 0, MaxValue: math.MaxInt64, IsHintUpdatableVerified: true, SetSession: func(s *SessionVars, val string) error {
 		s.PagingSizeBytes = int(TidbOptInt64(val, int64(vardef.DefPagingSizeBytes)))
 		return nil
 	}},
diff --git a/tests/integrationtest/r/sessionctx/setvar.result b/tests/integrationtest/r/sessionctx/setvar.result
index 91a7cfd9be050..a64e073b9fa49 100644
--- a/tests/integrationtest/r/sessionctx/setvar.result
+++ b/tests/integrationtest/r/sessionctx/setvar.result
@@ -1102,11 +1102,11 @@ select /*+ set_var(tidb_paging_size_bytes=1048576) */ @@tidb_paging_size_bytes;
 1048576
 select @@tidb_paging_size_bytes;
 @@tidb_paging_size_bytes
-0
+4194304
 set @@tidb_paging_size_bytes=default;
 select @@tidb_paging_size_bytes;
 @@tidb_paging_size_bytes
-0
+4194304
 set @@tidb_paging_size_bytes=0;
 select @@tidb_paging_size_bytes;
 @@tidb_paging_size_bytes
@@ -1118,7 +1118,7 @@ select @@tidb_paging_size_bytes;
 set @@tidb_paging_size_bytes=default;
 select @@tidb_paging_size_bytes;
 @@tidb_paging_size_bytes
-0
+4194304
 select /*+ set_var(tidb_enable_cascades_planner=0) */ @@tidb_enable_cascades_planner;
 @@tidb_enable_cascades_planner
 0