diff --git a/cmd/protoc-gen-go-http/http.go b/cmd/protoc-gen-go-http/http.go
index 3eb91c061..cebbb6b15 100644
--- a/cmd/protoc-gen-go-http/http.go
+++ b/cmd/protoc-gen-go-http/http.go
@@ -213,9 +213,9 @@ func buildPathVars(path string) (res map[string]*string) {
 	if strings.HasSuffix(path, "/") {
 		fmt.Fprintf(os.Stderr, "\u001B[31mWARN\u001B[m: Path %s should not end with \"/\" \n", path)
 	}
-	res = make(map[string]*string)
 	pattern := regexp.MustCompile(`(?i){([a-z\.0-9_\s]*)=?([^{}]*)}`)
 	matches := pattern.FindAllStringSubmatch(path, -1)
+	res = make(map[string]*string, len(matches))
 	for _, m := range matches {
 		name := strings.TrimSpace(m[1])
 		if len(name) > 1 && len(m[2]) > 0 {
diff --git a/config/value.go b/config/value.go
index 805f155e5..46417e773 100644
--- a/config/value.go
+++ b/config/value.go
@@ -93,9 +93,9 @@ func (v *atomicValue) Slice() ([]Value, error) {
 
 func (v *atomicValue) Map() (map[string]Value, error) {
 	if vals, ok := v.Load().(map[string]interface{}); ok {
-		m := make(map[string]Value)
+		m := make(map[string]Value, len(vals))
 		for key, val := range vals {
-			a := &atomicValue{}
+			a := new(atomicValue)
 			a.Store(val)
 			m[key] = a
 		}
diff --git a/contrib/registry/consul/client.go b/contrib/registry/consul/client.go
index 80ea383a6..e97ec7e42 100644
--- a/contrib/registry/consul/client.go
+++ b/contrib/registry/consul/client.go
@@ -95,7 +95,7 @@ func (c *Client) Service(ctx context.Context, service string, index uint64, pass
 
 // Register register service instance to consul
 func (c *Client) Register(_ context.Context, svc *registry.ServiceInstance, enableHealthCheck bool) error {
-	addresses := make(map[string]api.ServiceAddress)
+	addresses := make(map[string]api.ServiceAddress, len(svc.Endpoints))
 	checkAddresses := make([]string, 0, len(svc.Endpoints))
 	for _, endpoint := range svc.Endpoints {
 		raw, err := url.Parse(endpoint)
diff --git a/contrib/registry/discovery/discovery.go b/contrib/registry/discovery/discovery.go
index f6df56dc0..dfff0a972 100644
--- a/contrib/registry/discovery/discovery.go
+++ b/contrib/registry/discovery/discovery.go
@@ -439,7 +439,7 @@ func (r *Resolve) fetch(ctx context.Context) (ins *disInstancesInfo, ok bool) {
 		ins = new(disInstancesInfo)
 		ins.LastTs = appIns.LastTs
 		ins.Scheduler = appIns.Scheduler
-		ins.Instances = make(map[string][]*discoveryInstance)
+		ins.Instances = make(map[string][]*discoveryInstance, len(appIns.Instances))
 		for zone, in := range appIns.Instances {
 			ins.Instances[zone] = in
 		}
diff --git a/transport/grpc/balancer.go b/transport/grpc/balancer.go
index bd50f0983..2047eb0db 100644
--- a/transport/grpc/balancer.go
+++ b/transport/grpc/balancer.go
@@ -40,7 +40,7 @@ func (b *balancerBuilder) Build(info base.PickerBuildInfo) balancer.Picker {
 		// Block the RPC until a new picker is available via UpdateState().
 		return base.NewErrPicker(balancer.ErrNoSubConnAvailable)
 	}
-	nodes := make([]selector.Node, 0)
+	nodes := make([]selector.Node, 0, len(info.ReadySCs))
 	for conn, info := range info.ReadySCs {
 		ins, _ := info.Address.Attributes.Value("rawServiceInstance").(*registry.ServiceInstance)
 		nodes = append(nodes, &grpcNode{