diff --git a/go.mod b/go.mod
index ecbce71d..69dff731 100644
--- a/go.mod
+++ b/go.mod
@@ -29,7 +29,6 @@ require (
 	golang.org/x/exp v0.0.0-20240103183307-be819d1f06fc
 	golang.org/x/sync v0.7.0
 	golang.org/x/term v0.19.0
-	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
@@ -81,6 +80,7 @@ require (
 	golang.org/x/sys v0.19.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 	golang.org/x/tools v0.20.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 	gotest.tools/v3 v3.5.1 // indirect
 	mvdan.cc/gofumpt v0.6.0 // indirect
 )
diff --git a/pkg/cli/gptscript.go b/pkg/cli/gptscript.go
index c9c11396..40eda367 100644
--- a/pkg/cli/gptscript.go
+++ b/pkg/cli/gptscript.go
@@ -400,7 +400,7 @@ func (r *GPTScript) Run(cmd *cobra.Command, args []string) (retErr error) {
 
 	if prg.IsChat() || r.ForceChat {
 		return chat.Start(r.NewRunContext(cmd), nil, gptScript, func() (types.Program, error) {
-			return r.readProgram(ctx, gptScript, args)
+			return prg, nil
 		}, os.Environ(), toolInput)
 	}
 
diff --git a/pkg/hash/sha256.go b/pkg/hash/sha256.go
index 1bbb6117..05209e44 100644
--- a/pkg/hash/sha256.go
+++ b/pkg/hash/sha256.go
@@ -20,8 +20,15 @@ func ID(parts ...string) string {
 
 func Digest(obj any) string {
 	hash := sha256.New()
-	if err := gob.NewEncoder(hash).Encode(obj); err != nil {
-		panic(err)
+	switch v := obj.(type) {
+	case []byte:
+		hash.Write(v)
+	case string:
+		hash.Write([]byte(v))
+	default:
+		if err := gob.NewEncoder(hash).Encode(obj); err != nil {
+			panic(err)
+		}
 	}
 	return hex.EncodeToString(hash.Sum(nil))
 }
diff --git a/pkg/loader/github/github.go b/pkg/loader/github/github.go
index fc2e5f81..7b2ad240 100644
--- a/pkg/loader/github/github.go
+++ b/pkg/loader/github/github.go
@@ -8,10 +8,12 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/gptscript-ai/gptscript/pkg/cache"
 	"github.com/gptscript-ai/gptscript/pkg/loader"
+	"github.com/gptscript-ai/gptscript/pkg/mvl"
 	"github.com/gptscript-ai/gptscript/pkg/repos/git"
 	"github.com/gptscript-ai/gptscript/pkg/system"
 	"github.com/gptscript-ai/gptscript/pkg/types"
@@ -26,6 +28,7 @@ const (
 
 var (
 	githubAuthToken = os.Getenv("GITHUB_AUTH_TOKEN")
+	log             = mvl.Package()
 )
 
 func init() {
@@ -37,7 +40,14 @@ func getCommitLsRemote(ctx context.Context, account, repo, ref string) (string,
 	return git.LsRemote(ctx, url, ref)
 }
 
+// regexp to match a git commit id
+var commitRegexp = regexp.MustCompile("^[a-f0-9]{40}$")
+
 func getCommit(ctx context.Context, account, repo, ref string) (string, error) {
+	if commitRegexp.MatchString(ref) {
+		return ref, nil
+	}
+
 	url := fmt.Sprintf(githubCommitURL, account, repo, ref)
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
 	if err != nil {
@@ -69,6 +79,8 @@ func getCommit(ctx context.Context, account, repo, ref string) (string, error) {
 		return "", fmt.Errorf("failed to decode GitHub commit of %s/%s at %s: %w", account, repo, url, err)
 	}
 
+	log.Debugf("loaded github commit of %s/%s at %s as %q", account, repo, url, commit.SHA)
+
 	if commit.SHA == "" {
 		return "", fmt.Errorf("failed to find commit in response of %s, got empty string", url)
 	}
diff --git a/pkg/loader/loader.go b/pkg/loader/loader.go
index e9bbd1bf..81a65d29 100644
--- a/pkg/loader/loader.go
+++ b/pkg/loader/loader.go
@@ -20,10 +20,10 @@ import (
 	"github.com/gptscript-ai/gptscript/pkg/assemble"
 	"github.com/gptscript-ai/gptscript/pkg/builtin"
 	"github.com/gptscript-ai/gptscript/pkg/cache"
+	"github.com/gptscript-ai/gptscript/pkg/hash"
 	"github.com/gptscript-ai/gptscript/pkg/parser"
 	"github.com/gptscript-ai/gptscript/pkg/system"
 	"github.com/gptscript-ai/gptscript/pkg/types"
-	"gopkg.in/yaml.v3"
 )
 
 const CacheTimeout = time.Hour
@@ -120,6 +120,30 @@ func loadProgram(data []byte, into *types.Program, targetToolName string) (types
 	return tool, nil
 }
 
+func loadOpenAPI(prg *types.Program, data []byte) *openapi3.T {
+	var (
+		openAPICacheKey     = hash.Digest(data)
+		openAPIDocument, ok = prg.OpenAPICache[openAPICacheKey].(*openapi3.T)
+		err                 error
+	)
+
+	if ok {
+		return openAPIDocument
+	}
+
+	if prg.OpenAPICache == nil {
+		prg.OpenAPICache = map[string]any{}
+	}
+
+	openAPIDocument, err = openapi3.NewLoader().LoadFromData(data)
+	if err != nil || openAPIDocument.Paths.Len() == 0 {
+		openAPIDocument = nil
+	}
+
+	prg.OpenAPICache[openAPICacheKey] = openAPIDocument
+	return openAPIDocument
+}
+
 func readTool(ctx context.Context, cache *cache.Client, prg *types.Program, base *source, targetToolName string) (types.Tool, error) {
 	data := base.Content
 
@@ -127,17 +151,19 @@ func readTool(ctx context.Context, cache *cache.Client, prg *types.Program, base
 		return loadProgram(data, prg, targetToolName)
 	}
 
-	var tools []types.Tool
-	if isOpenAPI(data) {
-		if t, err := openapi3.NewLoader().LoadFromData(data); err == nil {
-			if base.Remote {
-				tools, err = getOpenAPITools(t, base.Location)
-			} else {
-				tools, err = getOpenAPITools(t, "")
-			}
-			if err != nil {
-				return types.Tool{}, fmt.Errorf("error parsing OpenAPI definition: %w", err)
-			}
+	var (
+		tools []types.Tool
+	)
+
+	if openAPIDocument := loadOpenAPI(prg, data); openAPIDocument != nil {
+		var err error
+		if base.Remote {
+			tools, err = getOpenAPITools(openAPIDocument, base.Location)
+		} else {
+			tools, err = getOpenAPITools(openAPIDocument, "")
+		}
+		if err != nil {
+			return types.Tool{}, fmt.Errorf("error parsing OpenAPI definition: %w", err)
 		}
 	}
 
@@ -263,6 +289,12 @@ func link(ctx context.Context, cache *cache.Client, prg *types.Program, base *so
 }
 
 func ProgramFromSource(ctx context.Context, content, subToolName string, opts ...Options) (types.Program, error) {
+	if log.IsDebug() {
+		start := time.Now()
+		defer func() {
+			log.Debugf("loaded program from source took %v", time.Since(start))
+		}()
+	}
 	opt := complete(opts...)
 
 	prg := types.Program{
@@ -292,6 +324,13 @@ func complete(opts ...Options) (result Options) {
 }
 
 func Program(ctx context.Context, name, subToolName string, opts ...Options) (types.Program, error) {
+	if log.IsDebug() {
+		start := time.Now()
+		defer func() {
+			log.Debugf("loaded program %s source took %v", name, time.Since(start))
+		}()
+	}
+
 	opt := complete(opts...)
 
 	if subToolName == "" {
@@ -346,15 +385,20 @@ func input(ctx context.Context, cache *cache.Client, base *source, name string)
 	return nil, fmt.Errorf("can not load tools path=%s name=%s", base.Path, name)
 }
 
-func isOpenAPI(data []byte) bool {
-	var fragment struct {
-		Paths map[string]any `json:"paths,omitempty"`
-	}
+func SplitToolRef(targetToolName string) (toolName, subTool string) {
+	var (
+		fields = strings.Fields(targetToolName)
+		idx    = slices.Index(fields, "from")
+	)
 
-	if err := json.Unmarshal(data, &fragment); err != nil {
-		if err := yaml.Unmarshal(data, &fragment); err != nil {
-			return false
-		}
+	defer func() {
+		toolName, _ = types.SplitArg(toolName)
+	}()
+
+	if idx == -1 {
+		return strings.TrimSpace(targetToolName), ""
 	}
-	return len(fragment.Paths) > 0
+
+	return strings.Join(fields[idx+1:], " "),
+		strings.Join(fields[:idx], " ")
 }
diff --git a/pkg/loader/openapi.go b/pkg/loader/openapi.go
index e77c9849..658a26ab 100644
--- a/pkg/loader/openapi.go
+++ b/pkg/loader/openapi.go
@@ -7,6 +7,7 @@ import (
 	"slices"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/getkin/kin-openapi/openapi3"
 	"github.com/gptscript-ai/gptscript/pkg/engine"
@@ -18,6 +19,12 @@ import (
 // The tool's Instructions will be in the format "#!sys.openapi '{JSON Instructions}'",
 // where the JSON Instructions are a JSON-serialized engine.OpenAPIInstructions struct.
 func getOpenAPITools(t *openapi3.T, defaultHost string) ([]types.Tool, error) {
+	if log.IsDebug() {
+		start := time.Now()
+		defer func() {
+			log.Debugf("loaded openapi tools in %v", time.Since(start))
+		}()
+	}
 	// Determine the default server.
 	if len(t.Servers) == 0 {
 		if defaultHost != "" {
diff --git a/pkg/repos/git/cmd.go b/pkg/repos/git/cmd.go
index a9eba5fe..ad6d7350 100644
--- a/pkg/repos/git/cmd.go
+++ b/pkg/repos/git/cmd.go
@@ -9,6 +9,9 @@ import (
 )
 
 func newGitCommand(ctx context.Context, args ...string) *debugcmd.WrappedCmd {
+	if log.IsDebug() {
+		log.Debugf("running git command: %s", strings.Join(args, " "))
+	}
 	cmd := debugcmd.New(ctx, "git", args...)
 	return cmd
 }
diff --git a/pkg/types/tool.go b/pkg/types/tool.go
index 7ef0d0fc..e698bdc4 100644
--- a/pkg/types/tool.go
+++ b/pkg/types/tool.go
@@ -36,9 +36,10 @@ func (e *ErrToolNotFound) Error() string {
 type ToolSet map[string]Tool
 
 type Program struct {
-	Name        string  `json:"name,omitempty"`
-	EntryToolID string  `json:"entryToolId,omitempty"`
-	ToolSet     ToolSet `json:"toolSet,omitempty"`
+	Name         string         `json:"name,omitempty"`
+	EntryToolID  string         `json:"entryToolId,omitempty"`
+	ToolSet      ToolSet        `json:"toolSet,omitempty"`
+	OpenAPICache map[string]any `json:"-"`
 }
 
 func (p Program) IsChat() bool {