diff --git a/api/runner/task.go b/api/runner/task.go
index e8619c997..03c0ee098 100644
--- a/api/runner/task.go
+++ b/api/runner/task.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/docker/cli/cli/config/configfile"
 	"github.com/fnproject/fn/api/runner/drivers"
+	"github.com/fnproject/fn/api/runner/protocol"
 	"github.com/fnproject/fn/api/runner/task"
 	docker "github.com/fsouza/go-dockerclient"
 )
@@ -62,6 +63,9 @@ type containerTask struct {
 func (t *containerTask) Command() string { return "" }
 
 func (t *containerTask) EnvVars() map[string]string {
+	if protocol.IsStreamable(protocol.Protocol(t.cfg.Format)) {
+		return t.cfg.BaseEnv
+	}
 	return t.cfg.Env
 }
 func (t *containerTask) Input() io.Reader {
@@ -82,9 +86,8 @@ func (t *containerTask) IdleTimeout() time.Duration     { return t.cfg.IdleTimeo
 func (t *containerTask) Logger() (io.Writer, io.Writer) { return t.cfg.Stdout, t.cfg.Stderr }
 func (t *containerTask) Volumes() [][2]string           { return [][2]string{} }
 func (t *containerTask) WorkDir() string                { return "" }
-
-func (t *containerTask) Close()                 {}
-func (t *containerTask) WriteStat(drivers.Stat) {}
+func (t *containerTask) Close()                         {}
+func (t *containerTask) WriteStat(drivers.Stat)         {}
 
 // Implementing the docker.AuthConfiguration interface.  Pulling in
 // the docker repo password from environment variables
diff --git a/api/runner/task/task.go b/api/runner/task/task.go
index 219c586a2..cc568ca38 100644
--- a/api/runner/task/task.go
+++ b/api/runner/task/task.go
@@ -16,7 +16,8 @@ type Config struct {
 	IdleTimeout  time.Duration
 	AppName      string
 	Memory       uint64
-	Env          map[string]string
+	BaseEnv      map[string]string // only app & route config vals [for hot]
+	Env          map[string]string // includes BaseEnv
 	Format       string
 	ReceivedTime time.Time
 	// Ready is used to await the first pull
diff --git a/api/runner/worker.go b/api/runner/worker.go
index 70cfe5f24..3964e89be 100644
--- a/api/runner/worker.go
+++ b/api/runner/worker.go
@@ -2,6 +2,7 @@ package runner
 
 import (
 	"context"
+	"crypto/sha1"
 	"errors"
 	"fmt"
 	"io"
@@ -132,8 +133,8 @@ func (h *htfnmgr) getPipe(ctx context.Context, rnr *Runner, cfg *task.Config) ch
 		h.RLock()
 	}
 
-	// TODO(ccirello): re-implement this without memory allocation (fmt.Sprint)
-	fn := fmt.Sprint(cfg.AppName, ",", cfg.Path, cfg.Image, cfg.Timeout, cfg.Memory, cfg.Format)
+	fn := key(cfg)
+
 	svr, ok := h.hc[fn]
 	h.RUnlock()
 	if !ok {
@@ -149,6 +150,28 @@ func (h *htfnmgr) getPipe(ctx context.Context, rnr *Runner, cfg *task.Config) ch
 	return svr.tasksin
 }
 
+func key(cfg *task.Config) string {
+	// TODO we should probably colocate this with Config, but it's kind of hot
+	// specific so it makes sense here, too (just brittle & hidden)
+
+	// return a sha1 hash of a (hopefully) unique string of all the config
+	// values, to make map lookups quicker [than the giant unique string]
+	hash := sha1.New()
+	fmt.Fprint(hash, cfg.AppName, "\x00")
+	fmt.Fprint(hash, cfg.Path, "\x00")
+	fmt.Fprint(hash, cfg.Image, "\x00")
+	for k, v := range cfg.BaseEnv {
+		fmt.Fprint(hash, k, "\x00", v, "\x00")
+	}
+	fmt.Fprint(hash, cfg.Timeout, "\x00")
+	fmt.Fprint(hash, cfg.IdleTimeout, "\x00")
+	fmt.Fprint(hash, cfg.Memory, "\x00")
+	fmt.Fprint(hash, cfg.Format, "\x00")
+
+	var buf [sha1.Size]byte
+	return string(hash.Sum(buf[:]))
+}
+
 // htfnsvr is part of htfnmgr, abstracted apart for simplicity, its only
 // purpose is to test for hot functions saturation and try starting as many as
 // needed. In case of absence of workload, it will stop trying to start new hot
diff --git a/api/server/runner.go b/api/server/runner.go
index 46ce41eab..365ccf124 100644
--- a/api/server/runner.go
+++ b/api/server/runner.go
@@ -156,12 +156,19 @@ func (s *Server) serve(ctx context.Context, c *gin.Context, appName string, rout
 		"FORMAT":  route.Format,
 	}
 
+	// TODO we could add... format, app_name, route from above (but nothing from the specific request)
+	baseVars := make(map[string]string, len(app.Config)+len(route.Config))
+
 	// app config
 	for k, v := range app.Config {
-		envVars[toEnvName("", k)] = v
+		k = toEnvName("", k)
+		envVars[k] = v
+		baseVars[k] = v
 	}
 	for k, v := range route.Config {
-		envVars[toEnvName("", k)] = v
+		k = toEnvName("", k)
+		envVars[k] = v
+		baseVars[k] = v
 	}
 
 	// params
@@ -177,6 +184,7 @@ func (s *Server) serve(ctx context.Context, c *gin.Context, appName string, rout
 	cfg := &task.Config{
 		AppName:      appName,
 		Path:         route.Path,
+		BaseEnv:      baseVars,
 		Env:          envVars,
 		Format:       route.Format,
 		ID:           reqID,